Glossary extracted starting with manual seeds, with PTM for the domain met and language EN

landward	Positioned or located away from a water body but towards the land.
modem	Device that allows two computers (which use binary data in the form of bits) to communicate using a telephone line (which uses tones)
chemical autotroph	Organism that uses the external energy found in chemical compounds to produce food molecules
system element	System elements are the kinds of things or substances composing the system
frequency modulation	A type of modulation in which the frequency of a continuous radio carrier wave is varied in accordance with the properties of a second (modulating) wave.
intertropical convergence zone	The boundary zone separating the northeast trade winds of the Northern Hemisphere from the southeast trade winds of the Southern Hemisphere.
radio frequency	The RF waves emanating from an antenna are generated by the movement of electrical charges in the antenna
central processing unit	Main part of a computer consisting of an arithmetic logic unit and a control unit
sea level pressure	The pressure value obtained by the theoretical reduction or increase of barometric pressure to sea-level.
humidity coefficient	A measure, proposed by Angstrom, of the precipitation effectiveness of a region.
boiling point	The temperature at which a liquid changes to a vaporous state
trace	Generally, an unmeasurable or insignificant quantity
stratovolcano	See composite volcano.
spectroheliograph	An instrument for taking photographs of an image of the sun in monochromatic light.
cameo	Computer-Aided Management of Emergency Operations
radiation	The emission of energy from an object in the form of electromagnetic waves and photons.
unstable/ instability	Occurs when a rising air parcel becomes less dense than the surrounding air
re-entrants	A prominent indentation in an escarpment, ridge or shoreline.
temperature	Temperature is defined as the measure of the average speed of atoms and molecules
flood control storage	Storage of water in reservoirs to abate flood damage.
surge	A large, destructive ocean wave caused by very low atmospheric pressure and strong winds
precipitable water	Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.
conduction	The transfer of heat by molecular activity from one substance to another, or through a substance
occluded front	A composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front
crest width	The thickness or width of a dam at the level of the crest (top) of the dam
watershed	Catchment area of a drainage basin.
backswamp	Marshy low lying area in a stream's floodplain
myctophobia	The fear of darkness.
creek	A small stream of water which serves as the natural drainage course for a drainage basin of nominal, or small size
second-day feet	The volume of water represented by a flow of one cubic foot per second for 24 hours; equal to 86,400 cubic feet
soil moisture	Moisture contained in the soil above the water table, including water vapor which is present in the soil pores
runoff	That part of precipitation that flows toward streams on the surface of the ground or within the ground
divergence	An atmospheric condition that exists when the winds cause a horizontal net outflow of air from a specific region.
medial moraine	Deposit of material found down the center of a glacier
recording potentiometer	An instrument which automatically records the voltage applied to it, as a function of time.
arid	A term used for an extremely dry climate
weather warning	Statement that dangerous weather is likely or is occurring
dissolved load	Portion of the stream load that is in solution in the flowing water.
velocity zones	Areas within the floodplain subject to potential high damage from waves
cloud tags	Ragged, detached cloud fragments; fractus or scud.
threatened species	Species that is still plentiful in its natural range but is likely to become endangered because of declining population numbers.
rainfall	The amount of precipitation of any type, primarily liquid
photosphere	Visible surface of Sun from which radiant energy is release.
global warming	The theory that increased concentrations of greenhouse gases are causing the Earths surface temperature to warm.
cation exchange capacity	The capacity of a soil to exchange cations with the soil solution
freezing point/freeze	The process of changing a liquid to a solid
nyquist velocity or interval	The maximum unambiguous velocity that can be measured by a Doppler radar.
niche	Adaptive role that a species has in a habitat
rainbow	Any one of a family of circular arcs consisting of concentric colored bands, arranged from red on the inside to blue on the outside, which may be seen on a "sheet" of water drops (rain, fog, spray)
latent heat of vaporization	The amount of heat energy required from the environment to change the state of a liquid to a gas
valley breeze	Local thermal circulation pattern found in areas of topographic relief
degree	A unit of angular measure
light	A humanly visible form of electromagnetic radiation
heavy snow warning	Its issued when a snowfall totaling 6 inches or more in 12 hours or less is expected
entrainment	One of three distinct processes involved in erosion
cathode ray tube	A television picture tube for image display.
random	Eluding precise prediction, completely irregular.
peak power	The amount of power transmitted by a radar during a given pulse
raindrop spectrograph	An instrument which automatically determines the size distribution of raindrops.
radiation	Energy transported through electromagnetic waves
lightning	Visible discharge of electricity created by thunderstorms.
maximum	The greatest value attained by a function, for example, temperature, pressure, or wind speed
explosive eruption	Volcanic eruption where high-viscosity granite-rich magma causes an explosion of ash and pyroclastic material
kettle moraine	An area of glaciofluvial influenced moraine deposits pitted with kames and kettle holes.
long-wave radiation	Radiation with wavelengths greater than 4 microns
predominant wind	It is the wind that in the forecasters judgment generates (or is expected to generate) the local component of the significant sea conditions across the forecast area.
ocean current	Large scale horizontal flow of ocean water that is persistent and driven by atmospheric circulation.
variable ceiling	A ceiling of less than 3,000 feet (900 meters) which rapidly increases or decreases in height by established criteria during the period of observation.
instrument data processing circuit	Data processing module that transforms data from the instrument output format into a designed data structure in netCDF format.
cloud fraction	Fraction of sky covered by clouds, observed directly or derived from SW irradiance.
adiabatic process	A thermodynamic change of state in a system in which there is no transfer of heat or mass across the boundaries of the system
gap	A spatial opening in a plant community
scale	A specific relative or proportional size or extent of a phenomena as measured through space and/or time.
hydrology	The study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface.
aerosol scattering	The scattering of radiative energy by processes at the aerosol and molecular level.
krypton	An inert gas
grid nephoscope	A direct-vision nephoscope constructed in the following manner: A grid-work of bars is mounted horizontally on the end of a vertical column and made free to rotate about the vertical axis
system attribute	A system attribute is the perceived characteristic of a system element
lithosphere	The solid, outer portion of the earth's crust coupled to the rigid upper mantle
gaia hypothesis	The Gaia hypothesis states that the temperature and composition of the Earth's surface are actively controlled by life on the planet
lid	See Cap.
special weather statement	This is used by the National Weather Service to provide additional information about expected or ongoing significant weather changes not covered in other statements
thermistor	A semiconductor which exhibits rapid and extremely large changes in resistance for relatively small changes in temperature.
migration	Movement of organisms in an intentional way between two points in space
spatial analysis	The examination of the spatial pattern of natural and human-made phenomena using numerical analysis and statistics.
rf	See radio frequency.
savart polariscope	A polariscope consisting of a specially constructed double plate polarizer and a tourmaline plate analyzer
categorical	A National Weather Service precipitation descriptor for a 80%, 90%, or 100% chance of measurable precipitation (0.01")
alkaline	Substance capable of neutralizing acid, with a pH greater than 7.0
funnel cloud	A tornado which is beginning its descent from the base of a cumulonimbus cloud
sea-level	The average surface elevation of the world's oceans.
semi-diurnal tide	Tides that have two high and two low waters per tidal period.
crack	A separation formed in an ice cover of floe that does not divide it into two or more pieces.
perturbations	Minor corrections to the Keplerian model of a satellite orbit as an ellipse of constant shape and orientation
subsolar point	The location on the Earth where the Sun is directly overhead
international date line	The line of longitude located at 180Â° East or West (with a few local deviations) where the date changes by a day
river	A long narrow channel of water that flows as a function of gravity and elevation across the Earth's surface
gale warning	A warning for marine interests for impending winds from 28 to 47 knots (32 to 54 miles per hour).
peak annual flow	The largest discharge produced by a stream during a one year period.
longitude	Longitude is a west-east measurement of position on the Earth
baud	Unit of signaling speed
longitude	The position of the Earths surface east or west of the Greenwich meridian.
winter	The coldest season of the year
place	A term used in geography that describes the factors that make the location of natural and human-made phenomena unique.
polar jet stream	A jet stream that is associated with the polar front in the middle and high latitudes
rain-free base	the dark underside of a cloud (its base) that has no visible precipitation falling from it
hail	A mixture of liquid and frozen precipitation
combined error	The total of all deviations of a transducer's output from a specified straight line in a constant environment.
microorganism	Extremely small organism that can only be seen using a microscope.
total radiation	The sum of solar and terrestrial radiation.
windward	Upwind side or side directly influenced to the direction that the wind blows from
watch box	Slang for a severe thunderstorm or tornado watch.
wet bulb thermometer	A thermometer used to measure the lowest temperature in the ambient atmosphere in its natural state by evaporating water from a wet muslin-covered bulb of a thermometer
precipitation	Any and all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground.
horst fault	A fault that is produced when two reverse faults cause a block of rock to be push up.
vorticity	A measure of the spin of a fluid, usually small air parcels
vernier scale	A small, moveable graduated scale adjacent and parallel to the main scale of an instrument
fahrenheit	The standard scale used to measure temperature in the United States; in which the freezing point of water is 32° and the boiling point is 212°.
haze	Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer
barrier winds	Refers to the westerly flow of air along the northern slope of the Brooks Range in northern Alaska that precedes the arrival of colder air from the north.
bandwidth	The number of cycles per second between the limits of a frequency band.
altostratus	A cloud belonging to a class characterized by a generally uniform gray sheet or layer, lighter in color than nimbostratus and darker than cirrostratus
adiabatic process	The change of temperature of air without transferring heat
stevenson screen	A type of instrument shelter
isoline	Lines on a map joining points of equal value.
cumulus humilis	Cumulus clouds with little or no vertical development characterized by a generally flat appearance
beaufort wind scale	A system of estimating and reporting wind speed, originally based on the effect of various wind speeds on the amount of canvas that a full-rigged nineteenth century frigate could carry.
half duplex	Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.
precession	The comparatively slow torquing of the orbital planes of all satellites with respect to the Earth's axis, due to the bulge of the Earth at the equator which distorts the Earths gravitational field
fingerboard	a thin piece of wood (or hard, smooth material) attached to the playing surface of the neck of a stringed instrument
dry adiabatic lapse rate	The rate of decrease of temperature with height when unsaturated air is lifted adiabatically (without exchange of heat with its surroundings)
subrefraction	Less than normal bending of light or a radar beam as it passes through a zone of contrasting properties, such as atmospheric density, water vapor, or temperature.
limnology	The branch of hydrology that pertains to the study of lakes.
bar	An obstacle formed at the shallow entrance to the mouth of a river or bay which empties into the ocean.
stratus	A cloud belonging to a class characterized by a gray, horizontal layer with a uniform base, found at a lower altitude than altostratus, usually below 8000 feet (2400 meters).
rain	A form of precipitation
mdc	See more developed country.
ukas	An acronym for United Kingdom Accreditation Service, the organization tasked by the British government with the maintenance and administration of national standards
gelisols	Soil order (type) of the United States Natural Resources Conservation Service Soil Classification System
spectrophotometer	A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.
soil profile	Vertical arrangement of layers or horizons in a soil.
perennial plant	Plant species that lives for more than two years.
stream	A long narrow channel of water that flows as a function of gravity and elevation across the Earth's surface
rain	Precipitation composed of liquid water drops more than 0.5 mm in diameter, falling in relatively straight, but not necessarily vertical, paths
paleolake	An ancient lake that existed in the past when hydrological conditions were different.
isobar	A line of equal or constant pressure.
maxwell's law	The statement that the viscosity of air is independent of the density of air.
altitude	Height above the Earth's surface.
wfo	A National Weather Service Weather Forecast Office.
instrument landing system	A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e
e. coli	A group of bacteria, Escherichia, that reside in the intestinal tracts of humans and many animals and can cause food poisoning, urinary infections and enteritis.
synoptic	In general, pertaining to or affording an overall view
newton	A unit of force that creates an acceleration on a mass of 1 kilogram equal to 1 meter per second with no friction and under the conditions of a vacuum.
dew	Water condensed onto objects at or near the ground, due to the fact that their temperatures have fallen below the dew point temperature of the surrounding air, but not below freezing.
snowflakes	Packets of falling snow formed when at least a few ice crystals are matted together
thermohaline	In oceanography, it pertains to when both temperature and salinity act together
focus	See earthquake focus.
continental drift	Theory that suggests that the Earth's crust is composed of several continental plates that have the ability to move
clear air turbulence	Name given to turbulence that may occur in perfectly clear air without any visual in warning in the form of clouds
scattering coefficient	A measure of the attenuation due to scattering of light as it traverses a medium containing scattering particles.
drainage basin	A part of the surface of the earth that is occupied by a drainage system, which consists of a surface stream or a body of impounded surface water together with all tributary surface streams and bodies of impounded surface water
meteorite	It's a meteor that reaches the Earth's surface.
instrument flight rules	A set of regulations set down by the U.S
evaporimeter	Same as atmometer.
bellani atmometer	An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.
qfe	Atmospheric pressure at field elevation.
real time	As it happens.
wave length	The least distance between particles moving in the same phase of oscillation of a wave
ice field	Large level area of glacial ice found covering a large expanse of land
gravity	Also known as atmospheric pressure.
clear ice	It is a glossy, clear or translucent ice formed by the relatively slow freezing of large supercooled droplets
alto	A prefix to cloud-type names for clouds generally found between 3000 and 7000 meters
ferricretes	Sedimentary rock created by the chemical precipitation of iron.
vorticity maximum	A center of vorticity, or the maximum of the vorticity field of a fluid
point discharge	Instantaneous rate of discharge, in contrast to the mean rate for an interval of time.
pioneer community	Community dominated by pioneer species of plants.
percolation	Vertical movement or infiltration of water from the Earth's surface to its subsurface
continental shelf	Shallow submerged margin of the continents that lies between the edge of the shoreline and the continental slope
climatic optimum	Warmest period during the Holocene epoch
air pressure	The force exerted on a surface by the weight of the air above it
meteor shower	An event when hundreds of meteors or shooting stars appear in the sky at a specific time.
compensated saddle	A saddle that is at an angle other than 90 degrees to the strings and/or has notches that help to make the intonation of each string more perfect by accommodating the differences in string thickness.
field capacity	The water remaining in a soil after the complete draining of the soil's gravitational water.
gauge relation	An empirical curve relating stream discharge or stage at a point on a stream to discharge or stage at one or more upstream points and, possibly, to other parameters
profiler	A type of Doppler radar that typically measures both wind speed and direction from the surface to 55,000 feet in the atmosphere.
human-land tradition	Academic tradition in modern Geography that investigates human interactions with the environment.
bit rate	The speed at which bits are transmitted, usually expressed in bits per second
deformation thermometer	A thermometer using transducing elements which deform with temperature
radiometer	An instrument for measuring radiant energy
mean low water	The average height of the daily low tides recorded over a 19-year period at a specific location.
watt	A metric unit of measurement of the intensity of radiation in Watts over a square meter surface (W/m2 or W m-2).
sea breeze	An daytime coastal breeze that blows onshore, from the sea to the land
clay atmometer	An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water
international geophysical year	By international agreement, a period during which greatly increased observation of worldwide geophysical phenomena is undertaken through the cooperative effort of participating nations
frost-point hygrometer	An instrument for measuring the frost point of the atmosphere.
satellite orbital elements	See Keplerian elements.
wind vane	An instrument used to determine wind direction.
isothermal layer	Atmospheric layer throughout which there is no change of temperature with height, i.e
forest	Ecosystem dominated by trees
major flooding	A general term including extensive inundation and property damage
saturation	The condition of the atmosphere when the amount of water vapor present is the maximum possible at the existing temperature.
initial loss	In hydrology, rainfall preceding the beginning of surface runoff
oligotrophic lake	Lake with a low supply of nutrients in its waters
filter	Device that while selectively passing desired frequencies removes undesired ones.
spring	The season between winter and summer
paranthelion	A refraction phenomenon similar to a parahelion, but occurring generally at a distance of 120° (occasionally 90° and 140°) from the sun, on the parhelic circle.
total lift	The upward force produced by the gas in a balloon
equator	Location on the Earth that has a latitude of 0°.
roll cloud	A relatively rare, low-level, horizontal, tube-shaped cloud
calorimeter	An instrument designed to measure quantities of heat
residual layer	The elevated portion of a convective boundary layer that remains after a stable boundary layer develops at the ground (usually in late afternoon or early evening) and cuts off convection.
zonal flow	Large-scale atmospheric flow in which the east-west component (i.e., latitudinal) is or dominant
stratigraphy	Subdiscipline of geology that studies sequence, spacing, composition, and spatial distribution of sedimentary deposits and rocks.
temperature	humidity, pressure, winds) at a given time.
knot	A nautical unit of speed equal to the velocity at which one nautical mile is traveled in one hour
bolson	Is a closed desert basin with no drainage outlet, surrounded by mountains.
live capacity	The total amount of storage capacity available in a reservoir for all purposes, from the dead storage level to the normal water or normal pool level surface level
gain factor	See gain.
erratic	A large rock boulder that has been transported by glaciers away from its origin and deposited in a region of dissimilar rock.
infiltration capacity	The maximum rate at which water can enter the soil at a particular point under a given set of conditions.
electromagnetic radiation	Energy propagated as time-varying electric and magnetic fields
backing	A counterclockwise shift in the wind direction in the Northern Hemisphere at a certain location
forel scale	A scale of yellows, greens, and blues for recording the color of sea water, as seen against the white background of a Secchi disk.
lithometeor	Atmospheric phenomena which affect the state of the atmosphere
salinity	A measure of the quantity of dissolved salts in sea water
geophysical focus areas	Six identified focus areas for ARM's data collection and research activities
phloem	Food conducting tissue in vascular plants.
law of basin areas	Morphometric relationship observed in the mean basin area size of stream segments of a particular classification order in stream channel branching
low latitudes	The latitude belt between 30 and 0 degrees North and South of the equator
cumuliform	Clouds composed of water droplets that exhibit vertical development
cheimatophobia	The fear of cold
paraselenic circle	A halo phenomenon consisting of a horizontal circle passing through the moon, corresponding to the parhelic circle through the sun
natural selection	Environment's influence on the reproductive success of individuals in a population
cloud top height	For a given cloud or cloud layer, the highest level of the atmosphere where cloud properties are detectable.
soil evaporimeter	Instrument used to measure the amount of water evaporated from the soil surface during a given time interval.
critical entrainment velocity	Velocity required to entrain a particular sized particle into the moving medium of air or water.
vernal equinox	The beginning of spring in the Northern Hemisphere
ecological niche	Is all of the physical, chemical and biological conditions required by a species for survival, growth and reproduction
damping ratio	A constant which describes the performance of a wind vane in response to a step change in wind direction
dust dome	Dome of air that surrounds a city created from the urban heat island effect that traps pollutants like particulate matter.
tm	See Thematic Mapper
advection fog	Fog that develops when warm moist air moves over a colder surface, cooling that air to below its dew point.
thermal low	Area of low pressure in the atmosphere caused by the area having cooler temperatures relative to the air around it.
cold front	A boundary between two air masses, one cold and the other warm, moving so that the colder air replaces the warmer air.
topex/poseidon	Ocean Topography Experiment, United States (NASA)/ France (CNES)
natural gas	Hydrocarbon based gas, mainly composed of methane, commonly found in the pores of sedimentary rocks of marine origin.
stadial moraine	See recessional moraine.
thermal highs	Areas of high pressure that are shallow in vertical extent and are produced primarily by cold surface temperatures.
hygrometer	An instrument that measures the water vapor content of the atmosphere.
temperature	Relative HumidityThe ratio of the vapor pressure to the saturation vapor pressure with respect to water
moderate gale	Wind with a speed between 28 and 33 knots (32 and 38 mph); Beaufort scale number 7.
eolian	Same as Aeolian.
koschmieder's law	A basic equation in daytime visual range theory, relating the apparent luminance of a distant black object, the apparent luminance of the background sky above the horizon, and the extinction coefficient of the air layer near the ground
photon	A discrete unit of radiant energy.
price meter	A current meter consisting of six conical cups, mounted around a vertical axis, which rotate and generate a signal with each rotation
thermostat	A device used to switch electrical current at a selectable setpoint temperature.
winds aloft	The wind speed and direction at various levels in the atmosphere above the level reached by surface weather observations.
geocoding	The conversion of features found on an analog map into a computer-digital form
hypsometer	An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or other liquids
propagation	The transmission of electromagnetic energy as waves through or along a medium.
oceanography	The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.
soil fertility	The ability of a soil to provide nutrients for plant growth.
basin	See river basin.
ocean	The intercommunicating body of salt water occupying the depressions of the earth's surface, or one of its major primary subdivisions, bounded by the continents, or the equator, and other imaginary lines
kelvin scale	Scale for measuring temperature
bedding plane	A layer in a series of sedimentary beds that marks a change in the type of deposits.
cloud	A visible aggregate of minute water droplets or ice particles in the atmosphere above the Earth's surface.
pressure	however it is always less than the DALR.
wave pole	A device for measuring sea-surface waves
subsea permafrost	Form of permafrost that exists beneath the sea in ocean sediments.
monthly climatological report	This climatological product is issued once a month by each National Weather Service office
universal time coordinate	One of several names for the twenty-four hour time which is used throughout the scientific and military communities.
frost	Precipitation - General name for water in any form falling from clouds
climate	General pattern of weather conditions for a region over a long period time (at least 30 years).
mass balance	The relative balance between the input and output of material within a system.
receiver	(1) The initial component or the sensing element of a measuring system
nva	An acronym for Negative Vorticity Advection.
sheet flow	Flow that occurs overland in places where there are no defined channels, the flood water spreads out over a large area at a uniform depth
canal	A man-made watercourse designed to carry qoods or water.
frost	Ice crystal deposits formed by sublimation (conversion of water vapor directly to ice) when temperature and dew point are below freezing.
fema	U.S
lysimeter	Meteorological instrument used to measure potential and actual evapotranspiration.
ice crystals	A type of precipitation composed of unbranched crystals in the form of needles, columns, or plates
hygroscopic	Readily taking up and retaining moisture.
paraselene	A weakly colored lunar halo identical in form and optical origin to the solar parhelion.
large-scale	See synoptic-scale.
sand	Mineral particle with a size between 0.06 and 2.0 millimeters in diameter
barrier island	Long, narrow islands of sand and/or gravel that are usually aligned parallel to the shore of some coasts.
hythergraph	A type of climatic diagram whose coordinates are some form of temperature vs
zulu time	One of several names for the twenty-four hour time which is used throughout the scientific and military communities
trough	Elongated area of low atmospheric pressure, either at the surface or in the upper atmosphere.
point bar	Stream bar deposit that is normally located on the inside of a channel bend.
afterbay	The tail race of a hydroelectric power plant at the outlet of the turbines
conformal coating	A protective coating applied to circuits.
sedimentary rock	Rocks formed by the deposition, alteration and/or compression, and lithification of weathered rock debris, chemical precipitates, or organic sediments
kingdom	Top most level of the common system used to classify life
unambiguous range	See maximum unambiguous range.
carbon cycle	Storage and cyclic movement of organic and inorganic forms of carbon between the biosphere, lithosphere, hydrosphere, and atmosphere.
absorptivity	The efficiency of radiation absorption.
radiosonde	A balloon-borne instrument for the simultaneous measurement and transmission of meteorological data
bergschrund	A deep crevasse commonly found at the head of an alpine glacier
seed	Fertilized ovule of a plant that contains an embryo and food products for germination
hydrologic accounting	A systematic summary of the terms (inflow, outflow, and storage) of the storage equation as applied to the computation of soil-moisture changes, ground-water changes, etc
permeability	A measure of the ability of soil, sediments, and rock to transport water horizontally and vertically
wet-bulb temperature	The lowest temperature that can be obtained by evaporating water into air.
coefficient of determination	Statistic that measures the proportion of the variation in the dependent variable that is associated with the statistical regression of an independent variable
oh	The Office of Hydrology, located in Silver Spring, MD.
striations	Grooves or channels in cloud formations, arranged parallel to the flow of air and therefore depicting the airflow relative to the parent cloud
syncline	A fold in rock layers that forms a trough-like bend.
altocumulus castellanus	They are middle level convective clouds and possibly they should be classified as clouds with extensive vertical development
low clouds	A term used to signify clouds with bases below 6,000 feet and are of a stratiform or a cumuliform variety
short wave	A small wave in the polar jet stream and the westerlies that extends from the middle to the upper troposphere
arctic	Of or relating to the area around the geographic North Pole, from 90° North to the Arctic Circle at approximately 66 1/2 North latitude.
hydrologic cycle	Often called the water cycle, it is the vertical and horizontal transport of water in all its states between the earth, the atmosphere, and the seas.
indicator	An instrument used to reveal but not necessarily measure the presence of an electrical quantity
isobar	A line connecting equal points of pressure.
gamete	A haploid reproductive cell.
rf	Abbreviation for radio frequency.
downdraft	A small-scale column of air that rapidly sinks toward the ground, usually accompanied by precipitation as in a shower or thunderstorm
kerfing	wedge-shaped strips of wood (with closely spaced slits in them) that smoothly conform to the inside surface of the sides of an instrument where they meet the top & back; kerfing increases surface area for gluing & reinforces the seams of the instrument
center	The vertical axis or core of a tropical cyclone
high seas forecasts	This National Weather Service High Seas Forecasts are designed to meet the needs of ships making ocean transits; therefore, the primary focus is on major weather systems and sea states affecting oceangoing vessels.
snotel	SNOw TELemetry
band	See frequency band.
temperature	relative humidity, precipitation, cloudiness, wind speed and direction observation
barrage	Any artificial obstruction placed in water to increase water level or divert it
moisture	Refers to the water vapor content in the atmosphere, or the total water, liquid, solid or vapor, in a given volume of air.
lake	A body of fresh or salt water entirely surrounded by land.
biogeochemical cycling	Cycling of a single element, compound or chemicals by various abiotic and biotic processes through the various stores found in the biosphere, lithosphere, hydrosphere, and atmosphere.
radiosonde	Also can indicate wind and dew point.
backsight	A rod reading taken on a point of known elevation, a benchmark or a turning point
frame	A single image or picture
limiting factor	Abiotic condition that most controls the growth of a species
hazard	Phenomenon which can cause loss of life, injury, disease, economic loss, or environmental damage.
stratus clouds	Low-lying, gray and sheetlike clouds that often produce drizzle
random	Process or event that occurs by chance.
cape	A piece of land extendinq into water.
evaporation fog	A type of fog produced from the advection of cold air over warm water or warm or moist land
cumulonimbus mammatus cloud	It is associated with a cumulonimbus cloud
matric force	Force that holds soil water from 0.0002 to 0.06 millimeters from the surface of soil particles
storm winds	On the Beaufort Wind Scale, a wind with speeds from 56 to 63 knots (64 to 72 miles per hour).
air pollution	The soiling of the atmosphere by contaminants to the point that may cause injury to health, property, plant, or animal life, or prevent the use and enjoyment of the outdoors.
condensation	The process by which water vapor undergoes a change in state from a gas to a liquid
radio frequency	A frequency that is useful for radio transmission, usually between 10 kHz and 300,000 MHz.
curvature	The reciprocal of the radius of a circle; the rate of change in the deviation of a given arc from any tangent to it.
x-rays	The portion of the electromagnetic spectrum that has a very short wave length
isostatic rebound	The upward movement of the Earth's crust following isostatic depression.
mos	An acronym for Model Output Statistics.
scanner	A system thal optically scans its detector(s) across a scene and records or stores the data in a two-dimensional format to form an image.
galilei	The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec²
grazing food chain	Model describing the trophic flow of organic energy in a community or ecosystem.
diffraction	The result of light waves interfering with other after passing through a narrow aperture, causing them to bend or spread.
boiling point	Temperature of equilibrium between the liquid and vapor phases of a substance at a given pressure.
charles' law	With constant pressure, the temperature of an ideal gas is inversely proportional to the density of the gas.
hydrometer	An instrument used for measuring the specific gravity of a liquid.
water table	The depth below which the ground is saturated with water
wind chill	The wind can reduce significantly the amount of heat your body retains
ombrometer	A rain gauge capable of measuring very small amounts of precipitation
front	An interface or zone of transition between two distinct air masses.
isotope	Form of an element where the number of neutrons in its atomic nucleus is different than the number of protons.
fs output	The transducer's output when the maximum sensed value is applied to the transducer's input
high pressure area	An area of cool sinking air.
barometry	The art or process of making barometrical measurements.
refraction	Changes in the direction of energy propagation as a result of density changes within the propagating medium
riffle	Bar deposit found on the bed of streams
ph	A symbol for the degree of acidity of alkalinity of solution
tropopause	The tropopause is a relatively thin atmospheric transition layer found between the troposphere and the stratosphere
temperature	The measure of molecular motion or the degree of heat of a substance
cooling degree day	A cooling degree day is given for each degree that the daily mean temperature departs above the baseline of 75 degrees Fahrenheit
zooplankton	Small heterotrophic organisms found inhabiting aquatic ecosystems
streamflow	Water flowing in the stream channel
biodegradation	Decomposition of material by microorganisms.
geostrophic wind	That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force
period	Time required for a satellite to make one complete orbit.
gain	The increase in signal power produced by an amplifier, usually expressed in decibels as the ratio of the output to the input
dalton's law	States that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the gases
advisory	Statements that are issued by the National Weather Service for probable weather situations of inconvenience that do not carry the danger of warning criteria, but, if not observed, could lead to hazardous situations
survey mode	Refers to observational emphasis upon frequent global coverage, usually with restricted spatial and spectral resolution, aimed at developing a consistent, long-term data product for later interpretation.
background noise	The total noise floor from all sources of interference in a measurement system, independent of the presence of a data signal.
rainstorm	a storm with rain
mars	Motor Aspirated Radiation Shield
ebert ion-counter	An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.
lichen	Organism that consists of a symbiotic joining of a species of fungi and a species of algae.
radioactive	Giving off or capable of giving off radiant energy in the form of particles or rays, as in alpha, beta, and gamma rays.
evaporation	A process by which liquid changes into a gas or vapor.
brackish	Environment that is influenced by seawater with a salinity less than 35 parts per thousand (usually caused by the presence of an inflow of fresh water).
rainbow	They are one of the most common but most spectacular sky displays
mud slide	Fast moving soil, rocks and water that flow down mountain slopes and canyons during a heavy a downpour of rain.
water	such as salt particles.
pulse	A short burst of electromagnetic energy that a radar sends out in a straight line to detect a precipitation target
stationary pressure	A front between warm and cold air masses that is moving very slowly or not at all.
mica	Silicate mineral that exhibits a platy crystal structure and perfect cleavage
surface moisture flux	The vertical flux of surface moisture due to atmospheric turbulent transport.
sea water thermometer	A thermometer designed for use in measuring the temperature of sea water
cirrus	They are thin, feather like clouds composed entirely of ice crystals
sea breeze front	A coastal phenomena, it is restricted to large bodies of water and their immediate coast lines
nimbus	The Latin word for "rain" used to describe a cloud or group of clouds from which rain is falling.
cpu	Central Processing Unit
hold	A feature common to thermometers allowing you to freeze the display at a given measurement without additional inputs for easier reading
baseline change request	A web-based tool that is used to discuss, review, and approve an "engineered product" or other changes to infrastructure components as it is turned over to ARM Operations.
freezing fog	Used to describe the phenomena when fog is present and the air temperature is below 0°C
mudflow	Form of mass movement where fine textured sediments and soil mix with water to create a liquid flow.
continent	One of the large, continuous areas of the Earth into which the land surface is divided
nipher shield	A conically shaped, copper rain gauge shield.
equator	An imaginary circle around the Earth that is everywhere equally distant (90 degrees from the North Pole and the South Pole
stratosphere	Atmospheric layer found at an average altitude of 11 to 50 kilometers above the Earth's surface
cation	An ion carrying a positive atomic charge.
conservation storage	Storage of water for later release for usual purposes such as municipal water supply, power, or irrigation in contrast with storage capacity used for flood control..
service hydrologist	The designated expert of the hydrology program at a local weather forecast office.
foot wall	The bottommost surface of an inclined fault.
wetland	Natural land-use type that is covered by salt water or fresh water for some time period
nsf certified	This icon indicates that the design, materials, production process and quality controls used in the production of a product have been verified and certified for food safety by a highly respected third party non-profit organization, the National Sanitation Foundation (NSF).
sunrise	The time the sun appears above the horizon.
condensation nuclei	A particle upon which condensation of water vapor occurs
frontogenesis	The process in which a front forms
protista	Group, at the kingdom level, in the classification of life
rip current	A strong, narrow current of surface water that flows seaward through the surf into deeper water
cretaceous	Geologic period that occurred roughly 65 to 144 million years ago
radio wave	An electrical impulse sent through the atmosphere at radio frequency.
blowing sand	Sand that is raised by the wind to heights of six feet or greater
snow shower	Frozen precipitation in the form of snow, characterized by its sudden beginning and ending
landslide	Term used to describe the downslope movement of soil, rock, and other weathered materials because of gravity.
caliche	An accumulation of calcium carbonate at or near the soil surface.
water-stage recorder	A device for obtaining a continuous record of stage at a point on a stream
el niño	Means literally, the Christ child, a name given to an extensive ocean warming in the equatorial eastern Pacific along the coast of Peru and Ecuador that often begins around Christmas (hence, the name)
smoke management	Conducting a prescribed fire or slash burn with firing techniques and meteorological conditions that keep the smoke's impact on the environment with acceptable limits.
greenhouse effect	Atmospheric heating caused by solar radiation being readily transmitted inward through the earth's atmosphere but longwave radiation less readily transmitted outward, due to absorption by certain gases in the atmosphere.
temperature	Relative Humidity - The ratio of water vapor contained in the air compared to the maximum amount of moisture that the air can hold at that particular temperature and pressure
convective clouds	The vertically developed family of clouds are cumulus and cumulonimbus
vertical wind profile	A series of wind direction and wind speed measurements taken at various levels in the atmosphere that show the wind structure of the atmosphere over a specific location
aerosol	Particles of liquid or solid dispersed as a suspension in gas.
aka	Also Known As.
barometric errors	See barometric corrections.
pluvial	Pertaining to rain, or more broadly, to precipitation.
dry slot	An area of dry, and usually cloud-free, air that wraps into the southern and eastern sections of a synoptic scale or mesoscale low pressure system
aurora	It is created by the radiant energy emission from the sun and its interaction with the earth's upper atmosphere over the middle and high latitudes
direct flood damage	The damage done to property, structures, goods, etc., by a flood as measured by the cost of replacement and repairs.
algorithm	A computer program (or set of programs) which is designed to systematically solve a certain kind of problem
gleysol soil	Soil order (type) of the Canadian System of Soil Classification
extratropical cyclone	Any cyclone that is no longer tropical in origin
mercury-in-steel thermometer	A liquid-in-metal thermometer in which mercury is enclosed in a steel envelope
hydrocarbon	Organic compound composed primarily of hydrogen and carbon atoms
horizon	One of several lines or planes used as reference for observation and measurement relative to a given location on the surface of the earth
jet streak	A region of accelerated wind speed along the axis of a jet stream.
artesian well	A well drilled into a confined aquifer with enough hydraulic pressure for the water to flow to the surface without pumping
ground blizzard warning	When blizzard conditions are solely caused by blowing and drifting snow.
nocturnal thunderstorms	Thunderstorms which develop after sunset
barometric correction table	Table or graph to facilitate compensation of the instrumental errors of a mercury barometer
lumen	A unit of luminous flux
dynamic metamorphism	Form of metamorphism that causes only the structural alteration of rock through pressure
intangible flood damage	Estimates of the damage done by disruption of business, danger to health, shock, and loss of life and in general all costs not directly measurable which require a large element of judgment for estimating.
rs422	A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.
net pyrgeometer	An instrument for measuring the difference between incoming and outgoing terrestrial radiation.
erosion	The removal of weathered sediment or rocks by the forces of wind, water, and ice.
cmos	Complementary Metal-Oxide Semiconductor
inosilicate	Subclass of the silicate class of minerals
sub-synoptic low	Essentially the same as mesolow.
mutation	Change in the structure of a gene or chromosome.
directional shear	The shear created by a rapid change in wind direction with height.
software	The programs and instructions which direct a computer.
rope	A narrow, often contorted condensation funnel usually associated with the decaying stage of a tornado
full duplex	Operation mode of a communication circuit in which each end can simultaneously transmit and receive.
time constant	The time required for an instrument to register 63.2% of a step change in the variable being measured.
firn line	See firn limit.
visibility	The greatest distance at which it is just possible to see and recognize with the unaided eye (1) in the daytime, a prominent dark object against the sky at the horizon, and (2) at night, a known, preferably unfocused, moderately intense light source.
second law of thermodynamics	This law states that heat can never pass spontaneously from a colder to a hotter body
gross secondary productivity	Total amount of chemical energy assimilated by consumer organisms.
ceiling projector	Same as ceiling light.
trace	Generally, an unmeasureable amount or insignificant quantity of precipitation in amount of less than 0.005 inch.
ceiling balloon	A small balloon used to determine the height of the cloud base
black ice	Thin, new ice on fresh or saltwater, appearing dark in color because of its transparency; also popularly applied to thin hazardous ice coverings on roads.
delay distance	The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction
swiftness	a rate (usually rapid) at which something happens
force of acceleration	Force resulting in the speed of a moving body to increase.
algorithm	A mathematical relation between an observed quantity and a variable used in a step-by-step mathematical process to calculate a quantity.
fern	A group of about 11,000 species of vascular seedless plants that belong to the division Pterophyta
venturi	An increase in the velocity of a fluid or gas due to the constriction of flow.
geoid	A surface of constant gravitational potential around the Earth - an averaged surface perpendicular to the force of gravity.
specialist species	Species that have a relatively narrow ecological niche
gravity dam	A concrete structure proportioned so that its own weight provides the major resistance to the forces exerted on it.
luminescence	Any emission of light at temperatures below that required for incandescence.
flood	High water flow or an overflow of rivers or streams from their natural or artificial banks, inundating adjacent low lying areas.
continental slope	Steeply sloping portion of continental crust found between the continental shelf and continental rise.
frozen precipitation	Precipitation that reaches the ground in a frozen state
resolution	The smallest detectable increment of measurement on an instrument
montreal protocol	Treaty signed in 1987 by 24 nations to cut the emissions of chlorofluorocarbons (CFCs) into the atmosphere
nist-traceable	Indicates that a given instrument has been calibrated using standards that have an accuracy certified by the National Institute of Standards and Technology (NIST).
shoreline	The line that separates a land surface from a water body
atmospheric response variables	Variables that reflect the response of the atmosphere to external forcing (e.g., temperature, pressure, circulation, and precipitation).
thermocouple	The sensor of a thermoelectric thermometer, consisting of electrically conducting circuit elements of two different thermoelectric characteristics joined at a junction.
arctic jet	The jet stream that is situated high in the stratosphere in and around the Arctic or Antarctic Circles
quick looks	Daily and weekly plots of ARM data that give users a browsable quick view of a subset of data available at the ARM Archive.
piping	The progressive development of internal erosion by seepage, appearing downstream as a hole or seam discharging water that contains soil particles.
potential evaporation	Same as evaporative power.
ebb current	the movement of a tidal current away form the coast or down an estuary
ecliptic	The sun's apparent path across the sky that tracks a circle through the celestial sphere.
remote sensor	Mechanical devices used to remotely sense an object or phenomenon.
swash	A thin sheet of water that moves up the beach face after a wave of water breaks on the shore.
attenuation	The decrease in the magnitude of current, voltage, or power of a signal in transmission between points
extratropical	A term used in advisories and tropical summaries to indicate that a tropical cyclone has lost its "tropical" characteristics
cooperating program	A program or agency supporting a specific ARM effort, such as a field campaign, wherein ARM provides the resources.
dune field	An extensive region covered by numerous sand dunes.
thunder snow	A wintertime thunderstorm from which falls snow instead of rain
ppb	See parts per billion.
tropical depression	A tropical cyclone in which the maximum sustained surface winds are 38 miles per hour (33 knots) or less
paleogeography	The study of ancient or prehistoric qeoqraphy.
sial layer	The part of the crust that forms the continents and is composed of relatively light, granitic rocks.
hydrologic year	Same as water year.
temperature	RELATIVE HUMIDITY - Percentage scale based on the difference between temperature and dewpoint
channel lead	An elongated opening in the ice cover caused by a water current.
intermountain high	An area of high pressure that occurs during the winter between the Rocky Mountains and the Sierra-Cascade ranges
lentic system	A nonflowing or standing body of fresh water, such as a lake or pond
infiltration	Movement of water through the soil surface into the soil, or the quantity of water entering the soil
ground water hydrology	The branch of hydrology that specializes in ground water; its occurrence and movements; its replenishment and depletion; the properties of rocks that control ground water movement and storage; and the methods of investigation and utilization of ground water.
pressure head	Energy contained by fluid because of its pressure, usually expressed in feet of fluid (foot pounds per pound).
wiresonde	An atmospheric sounding instrument which is supported by a captive balloon and used to obtain temperature and humidity data from the ground level to a height of a few thousand feet
meteorology	The scientific study of the atmosphere and its associated phenomena.
pangaea	Hypothetical super continent that existed in the geological past
clouds	A visible collection of tiny water droplets or, at colder temperatures, ice crystals floating in the air above the surface
black body	A hypothetical object that absorbs all of the radiation that strikes it; also emits radiation at a maximum rate for its given temperature.
triple point	The point at which any three atmospheric boundaries meet
reptile	Group of terrestrial vertebrate animals that includes turtles, tortoises, snakes, lizards, crocodiles, and alligators.
atmosphere	Relative Humidity- A measure of the amount of water vapor actually held by a specific volume of air in comparison to the maximum water vapor that air could hold at a constant temperature.
metabolism	Describes all of the enzymatic reactions performed by the cells of an organism.
bottomset bed	Horizontal deltaic deposit of alluvial sediment composed of fine silt and clay.
nautical mile	A unit of length used in marine navigation that is equal to a minute of arc of a great circle on a sphere
equilibrium	Equilibrium describes the average condition of a system, as measured through one of its elements or attributes, over a specific period of time.
thermograph	An instrument that measures and records air temperature.
haboob	Sudanese name for duststorm or sandstorm with strong winds that carry small particles of dirt or sand into the air, particularly severe in areas of drought.
hygroscopic coefficient	Maximum limit of hygroscopic water around the surface of a soil particle.
ttl	Transistor-Transistor Logic.
rotten ice	Ice in an advanced stage of disintegration.
longwave net radiation	The difference between upwelling and downwelling broadband longwave radiation.
snow squall	A heavy snow shower accompanied by sudden strong winds, or a squall.
a/d	Analog to Digital
isthmus	Narrow strip of land located between two bodies of water, connectinq two larqer land areas.
delta	An alluvial deposit, often in the shape of the Greek letter "delta", which is formed where a stream drops its debris load on entering a body of quieter water.
halos	Rings or arcs that encircle the sun or moon
drosometer	An instrument used to measure the amount of dew formed on a given surface.
perched groundwater	Local saturated zones above the water table which exist above an impervious layer of limited extent.
isophane	A line drawn through geographical points where a given seasonal biological event occurs on the same date.
earthquake	Is a sudden motion or trembling in the Earth
newtonian telescope	A reflecting type telescope with a 45° mirror, so that the primary image is observed through a hole in the side of the tube.
stable air	Air with little or no tendency to rise, that is usually accompanied by clear dry weather.
symbiotic mutualism	Mutualistic interaction where the species interact physically and their relationship is biologically essential for survival.
high	A region of high pressure, marked as a blue "H" on a weather map
storm hydrograph	A hydrograph representing the flow or discharge of water past a point on a river.
dds	Data Distribution System.
plant	Organisms belonging to the kingdom Plantae
clear	The state of the sky when no clouds or obscurations are observed or detected from the point of observation.
stream channel	Long trough-like depression that is normally occupied by the water in a stream.
percolation	The movement of water, under hydrostatic pressure, through the interstices of a rock or soil, except the movement through large openings such as caves
rain forest	A forest which grows in a region of heavy annual precipitation
herb	A nonwoody angiosperm whose above ground vegetation dies off seasonally.
katabatic wind	Local winds a result of cold, dense air flowing downhill.
infrastructure management board	ACRF management team that manages the overall budget, planning, user request screening, activity implementation, and impact assessments for the ARM Climate Research Facility.
seawater	The mixture of water and various dissolved salts found in the world's oceans and seas.
reach	The distance between two specific points outlining that portion of the stream, or river for which the forecast applies
night	The period of the day between dusk and dawn.
sink	The process of providing storage for a substance
fissionable isotope	Isotope that can undergo nuclear fission when hit by a neutron at the right speed
pluviograph	Same as recording rain gauge.
granitic magma	Felsic magma that generates mainly granitic rocks.
berm	Low hill of sand that forms along coastal beaches.
descending node	The point in a satellite's orbit at which it crosses the equatorial plane from north to south.
notch width	The 3 dB band width of a rejection filter.
nebulaphobia	The fear of fog
isotherms	Lines connecting points of equal temperature on a weather map.
permanent monument	Fixed monuments placed away from the dam which allow movements in horizontal and vertical control points on the dam to be monitored by using accurate survey procedures.
hudson bay low	An area of low pressure over or near the Hudson Bay area of Canada that often introduces cold air to the north central and northeast United States.
infrared radiation	Electromagnetic radiation lying in the wavelength interval between 0.8 micron and 1 millimeter
headwaters	Streams at the source of a river.
mobile facility	The ARM Mobile Facility (AMF) was first deployed in 2005; it consists of large shipping containers converted into laboratories
pressure characteristic	The pattern of the pressure change during the specified period of time, usually the three hour period preceding an observation
panchromatic	Sensitive to all or most of the visible spectrum.
pingo	A large conical mound that contains an ice core
tornado alley	The portion of the United States where tornadoes occur most frequently
day-second feet	Often abbreviated as DSF
field elevation	The officially designated elevation of an airport above mean sea level, taken as the highest point on any of the runways of the airport
total gross reservoir capacity	The total amount of storage capacity available in a reservoir for all purposes from the streambed to the normal water or normal water or normal pool surface level
uniformitarianism	Is a theory that rejects the idea that catastrophic forces were responsible for the current conditions on the Earth
inactive storage capacity	The portion of capacity below which the reservoir is not normally drawn, and which is provided for sedimentation, recreation, fish and wildlife, aesthetic reasons, or for the creation of a minimum controlled operational or power head in compliance with operating agreements or restrictions.
rotational slip	Form of mass movement where material moves suddenly along a curvilinear plane
devonian	Geologic period that occurred roughly 360 to 408 million years ago
psk	Phase Shift Keying
climate analysis center	The U.S
evaporation hook gauge	See hook gauge.
background extinction	Normal extinction of species that occurs as a result of changes in local environmental conditions
spring tide	Tide that occurs every 14 to 15 days and coincides with the new and full moon
ice age	Period of time when glaciers dominate the landscape of the Earth
loess	Deposits of silt laid down by aeolian processes over extensive areas of the mid-latitudes during glacial and postglacial times.
dry weather flow	Streamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel
transpiration	The process by which water in plants is transferred as water vapor to the atmosphere
blowing snow	Wind-driven snow that significantly reduces surface visibility to less than 7 miles.
retreater	A defective maximum thermometer of the liquid-in-glass type in which the mercury flows too freely through the constriction
terrestrial radiation	The total infrared radiation emitted from the earth's surface
valley wall	The side slope of a stream or glacial valley.
minimum thermometer	Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day.
site-specific	Term used in conjunction with "forecast" or "warning" to convey the fact that a hydrologic (stream) forecast is produced for an individual stream gage location as opposed to a general area (e.g., a city, zone, or county) as is commonly done in many types of weather forecasts.
precipitation-evaporation quotient	A measure of long-term precipitation effectiveness
drift	The change in the readings or measurement values of an instrument at a set point over time
resolution cell	The smallest unit of area in an image of discrete elements
carrier wave	Transmitted energy which is modulated in order to carry information
fire-danger meter	A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index)
volcano	An elevated area of land created from the release of lava and ejection of ash and rock fragments from and volcanic vent.
dropsonde	A radiosonde dropped with a parachute from an aircraft rather than lifted by a balloon to measure the atmosphere below.
ordovician	Geologic period that occurred roughly 438 to 505 million years ago
metamorphic rock	A rock that forms from the recrystallization of igneous, sedimentary or other metamorphic rocks through pressure increase, temperature rise, or chemical alteration.
snow line	Altitudinal or latitudinal limit separating zones where snow does not melt during the summer season from areas in which it does
solar system	The collection of celestial bodies that orbit around the Sun.
stratosphere	The layer of the atmosphere above the troposphere, where temperature increases with height.
smoke	Small particles produced by combustion that are suspended in the air
genus	A group in the classification of organisms
realized niche	Describes the part of the fundamental niche that a species actually occupies.
scada	Supervisory Control and Data Acquisition
urbanization	Expansion of cities into rural regions because of population growth
pyramid of biomass	Graphic model describing the distribution of biomass in an ecosystem or community at the trophic level
fixed energy	A process, like photosynthesis, where organisms repackage inorganic energy into organic energy.
hurricane	They are intense storms with swirling winds up to 150 miles per hour
unconformity	A break in the sequence of sedimentary strata
sugar	Type of carbohydrate chemically based on carbon, oxygen, and hydrogen.
homosphere	The lower layer in a two part classification of the atmosphere based on the general homogeneity of chemical composition
colorado low	A low pressure disturbance that forms in the lee of the Rocky Mountains, usually in southeastern Colorado.
hardpan	Impervious layer found within the soil
snow pellets	Frozen precipitation in the form of white, round or conical opaque grains of ice
stationary front	A front that barely moves with winds blowing in almost parallel, but in opposite directions on each side of the front
snow line	The lowest elevation area of a perennial snow field on high terrain, such as a mountain range.
barograph	A recording barometer.
epoch	Geologic time unit that is shorter than a period.
facilitation model of succession	This model of succession suggests that the change in plant species dominance over time is caused by modifications in the abiotic environment that are imposed by the developing community
flood stage	The level at which a stream, river or other body of water begins to or will begin to leave its banks.
supercooled water	Liquid water at temperatures colder than freezing.
universe	All of the observable phenomena in the celestial cosmos.
balloon drag	A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.
recreation report	This product is used to relay reports on conditions for resorts and recreational areas and/or events
land breeze	A diurnal coastal breeze that blows offshore, from the land to the sea
comb nephoscope	A direct-vision nephoscope which is constructed in the following manner: a comb consisting of a cross-piece containing equispaced vertical rods is attached to one end of a column eight to ten feet long and is supported on a mounting that is free to rotate about its vertical axis
medium range	In forecasting, (generally) three to seven days in advance.
bracing	supportive wooden struts that strengthen instruments and affect tone; violin-family instruments have a single brace called a, “tone bar” that lies under the bass foot of the bridge; mandolins and guitars have various patterns of struts depending on the structure of the instrument, the kind of strings the instrument supports and the kind of tone that the builder tries to achieve
sandstone	A type of sedimentary rock that contains a large quantity of weathered quartz grains.
inversion	A layer in the atmosphere where the temperature increases with height.
nasda	See Japanese National Space Development Agency.
sunrise	Moment of time when the Sun's edge first appears above the Earth's horizon.
quality of snow	the amount of ice in a snow sample expressed as a percent of the weight of the sample.
geosphere	The physical elements of the Earth's surface, crust, and interior.
kilohertz	One thousand hertz, i.e., one thousand cycles per second.
drainage wind	A wind common to mountainous regions that involves heavy cold air flowing along the ground from high to low elevations because of gravity
sun	The closest star to Earth (149,599,000 km away on average)
convergence	A contraction of a vector field; the opposite of divergence
batholith	A large mass of subsurface intrusive igneous rock that has its origins from mantle magma.
recharge area	The area on the Earth's surface that receives water for storage into a particular aquifer.
induction	Inference of a generalized conclusion from particular instances
echo	The energy return of a radar signal after it has hit the target.
radar reflectivity	A measure of the efficiency of a radar target intercepting and returning radio energy
geodesy	The science that measures the surface features of the Earth.
rainbow	An arc that exhibits in concentric bands the colors of the spectrum and is formed opposite the sun by refraction and reflection of the sun's rays in rain drops.
fault scarp	The section of the fault plane exposed in a fault
till	Heterogeneous sediment deposited directly by a glacier
acre-foot	The amount of water required to cover one acre to a depth of one foot
staff gauge	A graduated scale placed in a position so that the stage of a stream may be read directly from it
tidal current	Regional scale ocean current that is created the tidal rise and fall of the ocean surface.
resonance	The state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus is the same, or nearly the same, as the natural vibration frequency of the system.
ice nuclei	Particles that act as nuclei for the formation of ice crystals in the atmosphere.
pers sunshine recorder	A sunshine recorder of the type in which the time scale is supplied by the motion of the sun
wind wave	An ocean or lake wave resulting from the action of wind on the water's surface
sleet	Frozen or partly frozen rain.
ion	An atom, molecule or compound that carries either a positive (cation) or negative (anion) electrical charge.
severe weather	Generally, any destructive weather event, but usually applies to localized storms, such as blizzards, intense thunderstorms, or tornadoes.
tolerance range	Limits of tolerance a species has to an abiotic factor or condition in the environment.
hail	Precipitation composed of balls or irregular lumps of ice
virtual temperature	Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.
coaxial cable	A hollow copper cylinder, or other cylindrical conductor, surrounding a single-wire conductor having a common axis (hence coaxial)
irrigation efficiency	The percentage of water applied that can be accounted for in soil moisture increase for consumptive use.
northeast trade winds	See trade winds.
initial detention	The volume of water on the ground, either in depressions or in transit, at the time active runoff begins.
drought	A period when a region has a lack of rainfall
solid	A state of matter where molecules where the mass of the substance does not have the property of flow.
snout	Front end of a glacier
stratiform	A cloud having predominantly horizontal development.
r&d	Research and Development.
sea stack	A steep pillar of rock located in the ocean a short distance from the coastline
obsidian	Glassy dark colored volcanic rock
drift	Any material deposited by a glacier.
headwater advisory table	A table developed by a River Forecast Center for a Headwater Guidance Point; a pre-computed matrix of values allows a forecaster to ascertain an anticipated crest or rise on a small river or stream for a variety of rainfall events and soil moisture conditions.
solar wind	Mass of ionized gas emitted to space by the Sun
isopluvial	A line drawn through geographical points having the same pluvial index.
radar	An electronic instrument, which determines the direction and distance of objects that, reflect radio energy back to the radar site
maximum spillway discharge	Spillway discharge (cfs) when reservoir is at maximum designed water surface elevation.
effluent stream	Any watercourse in which all, or a portion of the water volume came from the Phreatic zone, or zone of saturation by way of groundwater flow, or baseflow.
vernal equinox	One of two days during the year when the declination of the Sun is at the equator
rotation	The spinning of a body, such as the earth, about its axis.
theory	Proposed explanation for the causal mechanisms responsible for a phenomenon or a set of facts
clear sky	When the sky has no clouds.
cyclogenesis	The process that creates a new low pressure system or cyclone, or intensifies a pre-existing one
air	but not considering any liquid or ice content.
particulate matter	Particles of dust, soot, salt, sulfate compounds, pollen, or other particles suspended in the atmosphere.
clouds	Precipitation 1
magnetograph	A recording magnetometer.
robitzsch actinograph	A pyranometer developed by M
action	the distance between the strings and fingerboard or frets; excessively high action makes the strings hard to press; excessively low action causes buzzing.
water cycle	Also called the hydrologic cycle, it is the vertical and horizontal transport of water in all its states between the earth, the atmosphere, and the seas.
property protection	Measures that are undertaken usually by property owners in order to prevent, or reduce flood damage
tissue	A group of similar cells that are organized into a structure with a specific purpose.
crop calendar	The schedule of the maturing and harvesting of seasonal crops.
chemosynthesis	Process in which specific autotrophic organisms extract inorganic compounds from their environment and convert them into organic nutrient compounds without the use of sunlight
solar radiation shield	See radiation shield.
potential energy	The energy that a body possesses by virtue of its position with respect to other bodies in the field of gravity.
zulu time	One of several names for the twenty-four hour time which is used throughout the scientific and military communities.
rain	snow or sleet, ...
global warming	Warming of the Earth's average global temperature because of an increase in the concentration of greenhouse gases
true north	Direction of the North Pole from an observer on the Earth.
sea rainbow	Same as marine rainbow.
aeration zone	A portion of the lithosphere in which the functional interstices of permeable rock or earth are not filled with water under hydrostatic pressure
circle of illumination	A line that bisects areas on the Earth receiving sunlight and those areas in darkness
impermeable	Material that does not permit fluids to pass through it.
ampere	Standard unit to measure the strength of an electric current
green flash	A brilliant green coloration of the upper edge of the sun, occasionally seen as the sun's apparent disk is about to set below a clear horizon.
arctic air	An air mass that originates over Canada and brings us cold temperatures.
tercentesimal thermometric scale	Sir Napier Shaw's name for the approximate absolute temperature scale.
levee	Ridge of coarse deposits found alongside the stream channels and elevated above the floodplain
pollutant	A substance that has a harmful effect on the health, survival, or activities of humans or other living organisms.
oblique aerial photograph	Photograph taken from a non-perpendicular angle from a platform in the atmosphere.
snow showers	Brief occurrences of light to moderate snow, which could produce some snowfall accumulations.
glime	An ice coating with a consistency intermediate between glaze and rime.
return flow	South winds on the back (west) side of an eastward-moving surface high pressure system
condensation	The process by which a gas or vapor changes into a liquid.
median	Statistical measure of central tendency in a set of data
synchronous	Having a specific relationship to a time base or clock
eprom	Erasable Programmable Read Only Memory
dynamic range	The ratio, usually expressed in decibels, of the maximum to the minimum signal that a system can handle
pressure jump	A sudden, significant increase in station pressure.
ebris flow	A type of mass movement where there is a downslope flow of a saturated mass of soil, sediment, and rock debris.
human geography	Field of knowledge that studies human-made features and phenomena on the Earth from a spatial perspective
energy dissipater	A structure which slows fast-moving spillway flows in order to prevent erosion of the stream channel.
esa	European Space Agency
mesoscale convective complex	A large mesoscale convective system (MCS) which is about the size of the state of Ohio or Iowa and lasts at least 6 hours
mass movement	General term that describes the downslope movement of sediment, soil, and rock material.
drought	A period of abnormally dry weather sufficiently prolonged from the lack of precipitation to cause a serious hydrologic imbalance.
sun	Luminous star around which the Earth and other planets revolve around
heel block	also called a neck block - a piece of hardwood that supports the neck-to-body joint.
small craft advisory	A small craft advisory is a type of warning issued by the National Weather Service, most frequently in coastal areas
correlation coefficient	Statistic that measures the degree of linear association between two variables
silt	Mineral particle with a size between 0.004 and 0.06 millimeters in diameter
habitat	Location where a plant or animal lives.
reflector	In general, any object that reflects incident energy
small craft advisory	An advisory issued for marine interests, especially for operators of small boats or other vessels
tropical storm	Its a low-pressure disturbance that forms over warm tropical ocean waters
ground-hog day	February 2nd
continental air mass	An air mass with continental characteristics
critical depth	The depth of water flowing in an open channel or conduit, partially filled, corresponding to one of the recognized critical velocities.
atmosphere	the mass of air surrounding the earth and bound to it more or less permanently by the earth's gravitational attraction
electrometer	An instrument for measuring differences of electric potential.
salmonella	A rod-shaped bacteria common to food, particularly chicken and chicken products like eggs
emissivity	A measure of the energy-emitting propensity of a surface, usually measured at a specific wavelength
military grid reference system	A simplified subset of the Universal Transverse Mercator (UTM) Grid System
psychrometric table	Table of values that allows for the determination of relative humidity and dew point from dry-bulb and wet-bulb temperatures recorded on a psychrometer.
neutral atmosphere	Condition in the atmosphere where isolated air parcels do not have a tendency to rise or sink
anabranch	A diverging branch of a river which re-enters the main stream.
high pressure	Relative Humidity is one of several methods used to express the water vapor content of the air.It is the ratio between the amount of water vapor the air is actually holding at a certain temperature and expressed in percentage.
current meter	Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.
decay	See period decay
upper air	That portion of the atmosphere which is above the lower troposphere
bottle thermometer	A thermoelectric thermometer used for measuring air temperature
glacial retreat	The backwards movement of the snout of a glacier.
data acquisition	The process by which events in the real world are translated into machine-readable signals.
fracture	Any break or rupture formed in an ice cover or floe due to deformation.
calibration error	The inaccuracy that the manufacturer permits when the unit is calibrated in the factory.
subtropical jet	This jet stream is usually found between 20° and 30° latitude at altitudes between 39,000 and 46,000 feet (12 and 14 kilometers).
precipitation-evaporation ratio	For a given locality and month, an empirical expression devised for the purpose of classifying climates numerically on the basis of precipitation and evaporation.
miners' inch	A rate of discharge through an orifice one inch square under a specific head.
river gauge	A device for measuring the river stage
plane of the ecliptic	Hypothetical two-dimensional surface in which the Earth's orbit around the Sun occurs.
loaded gun	Slang for a sounding characterized by extreme instability but containing a cap, such that explosive thunderstorm development can be expected if the cap can be weakened or the air below it heated sufficiently to overcome it.
sclerophyllous vegetation	Term used to describe drought resistant vegetation common in Mediterranean climates
sunset	The daily disappearance of the sun below the western horizon as a result of the earth's rotation
value-added product	Physical models using ARM instrument data as inputs used to fulfill some of the unmet measurement needs of the ARM Program and to improve the quality of existing measurements.
keystone species	Species that interacts with a large number of other species in a community
base flow	Rate of discharge in a stream where only the throughflow and groundwater flow from subsurface aquifers contribute to the overall flow.
sea smoke	See evaporation fog.
transpiration	Water discharged into the atmosphere from plant surfaces.
inaccuracy	The difference between the input quantity applied to a measuring instrument and the output quantity indicated by the instrument
snow advisory	Its issued when a snowfall is expected to exceed 2 inches but no more than 5 inches.
roman	Real-Time Observations Monitor and Analysis Network
air	compared to the amount the air could hold if it was totally saturated
desert	A land area so dry that little or no plant or animal life can survive.
backlash	The play or loose motion in an instrument due to the clearance existing between mechanically contacting parts.
ripple	Stream bed deposit found streams
hydrograph	A graph showing the water level (stage), discharge, or other property of a river with respect to time
vfr	Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.
volume	The occupation of space in three dimensions
rain foot	Slang for a horizontal bulging near the surface in a precipitation shaft, forming a foot-shaped prominence
boundaries	Lines indicating the limits of countries, states, or other political jurisdictions, or different air mssses
fog bow	A nebulous arc or circle of white or yellowish light sometimes seen in fog.
snowburn	A burn of the skin, like a sunburn, but caused by the sun's rays reflected off the snow surface.
convectional precipitation	Is the formation of precipitation due to surface heating of the air at the ground surface
melting point	The temperature at which a solid substance undergoes fusion, i.e
humidity	Generally, a measure of the water vapor content of the air
surface pressure	The pressure that is read from a barometer but is not adjusted to sea level.
carbonate	Compound consisting of a single atom of carbon and three atoms of oxygen
telephony	Used to transmit sounds between widely removed points with or without connecting wires.
lightning ground flash density	The number of cloud-to-ground flashes per unit time per unit area.
geostrophic wind level	The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral
pilot report	A report of in-flight weather by an aircraft pilot or crew member
photochemical smog	A type of smog that forms in large cities when chemical reactions take place in the presence of sunlight, its principal component is ozone
condensation nuclei	Microscopic particle of dust, smoke or salt that allows for condensation of water vapor to water droplets in the atmosphere
flat top	a nickname for guitars with “flat” soundboards & steel strings
newhall winds	The local name for winds blowing downward from desert uplands through the Newhall Pass southward into the San Fernando Valley, north of Los Angeles.
general circulation models	A numerical representation of the climate system based on the physical, chemical, and biological properties of its components, their interactions, and feedback processes
hygrometer	An instrument which measures the humidity of the air.
low pressure area	An area of warm rising air.
hydrostatic head	A measure of pressure at a given point in a liquid in terms of the vertical height of a column of the same liquid which would produce the same pressure.
terabit	A trillion ( 1,000,000,000,000) bits.
eutrophication	The process whereby a body of water becomes rich in dissolved nutrients through natural or man-made processes
fog	A cloud on the ground that reduces visibility.
modulation	Variation in the frequency of a radio wave in accordance with some other impulse
shear stress	Stress caused by forces operating parallel to each other but in opposite directions.
prime meridian	The location from which meridians of longitude are measured
gain	An increase or amplification
evapotranspiration	Combined loss of water to the atmosphere via the processes of evaporation and transpiration.
neutralism	Interspecific interaction where the species do not directly influence each other fitness.
saturate	To treat or charge something to the point where no more can be absorbed, dissolved, or retained
dis	Data and Information System
equilibrium drawdown	The ultimate, constant drawdown for a steady rate of pumped discharge.
exosphere	This region is considered the very outer limits of the earth's atmosphere
nitric oxide	A gas produced by bacterial action in the soil and by high temperature combustion
bank	The margins of a channel
hook or hook echo	A pendant or hook on the right rear of a radar echo that often identifies mesocyclones on the radar display
aphelion	The point on the earth's orbit that is farthest from the sun
cumuliform	Having the appearance or character of cumulus clouds.
precipitation-effectiveness index	For a given location, a measure of the long-range effectiveness of precipitation in promoting plant growth
canadian high	High pressure system that develops in winter over central North America.
humidity	a topic about which Meadowood nags
river forecast	A forecast of the expected stage or discharge at a specified time, or of the total volume of flow within a specified interval of time, at one or more points along a stream.
cup anemometer	An instrument used to monitor wind speed
ohm	The unit of electrical resistance, equal to the resistance of a circuit in which an electromotive force of one volt maintains a current of one ampere
active storage capacity	The total amount of reservoir capacity normally available for release from a reservoir below the maximum storage level
isodrosotherm	A line on a chart connecting points of equal dewpoint.
false color	See digital image.
proxy data	Data that measures the cause and effect relationship between two variables indirectly.
comma cloud	A feature seen on satellite images with a distinctive comma-shape
vertical temperature profile	A series of temperature measurements taken at various levels in the atmosphere that show the thermal structure of the atmosphere over a specific location
advection	The horizontal transfer of any property in the atmosphere by the movement of air (wind)
ozone layer	Atmospheric concentration of ozone found at an altitude of 10 to 50 kilometers above the Earth's surface
stratocumulus clouds	Low altitude gray colored cloud composed of water droplets that has a patchy appearance
rotor cloud	An altocumulus cloud formation that can be found in the lee of a mountain or similar barrier
cloud height	The height of the cloud base above the local terrain.
landfall	The coastline location where a tropical storm or hurricane moves from ocean onto land.
detritus	Shed tissues, dead body parts, and waste products of organisms
habitat	The area or region where a particular type of plant or animal lives and grows.
biotic potential	Maximum rate that a population of a given species can increase in size (number of individuals) when there are no limits on growth rate.
sediment	Solid material that has been or is being eroded, transported, and deposited
artificial intelligence	Neural networks
thermal metamorphism	Is the metamorphic alteration of rock because of intense heat released from processes related to plate tectonics.
pascal's law	When an external pressure is applied to any confined fluid at rest, the pressure is increased at every point in the fluid by the amount of external pressure applied
eolian landform	Is a landform formed from the erosion or deposition of weathered surface materials by wind
eustacy	Variations in sea-level that are related to changes in the volume of seawater in the oceans.
tree	A large woody plant that has a trunk which supports branches and leaves.
upstream	Toward the source of the flow, or located in the area from which the flow is coming.
coral	Simple marine animals that live symbiotically with algae
law of the minimum	This biological law suggests that organisms are normally limited by only one single physical factor that is in shortest supply relative to demand.
imager	A satellite instrument that measures and maps the Earth and its atmosphere
virus	Is a fragment of DNA or RNA that depends on the infection of host cells for their reproduction
solar year	The time it takes the Earth to make one orbit around the Sun
skylab	The first U.S
non-clastic sedimentary rock	Sedimentary rocks that are created either from chemical precipitation and crystallization, or by the lithification once living organic matter.
heat stroke	Introduced to the body by overexposure to high temperatures, particularly when accompanied by high humidity
exosphere	The uppermost layer of the atmosphere, its lower boundary is estimated at 500 km to 1000 km above the Earth's surface
ice	A water substance in the solid phase.
multiplexer	A device that combines several separate communications signals into one and outputs them on a sinqle line.
santa ana winds	The hot, dry winds, generally from the east, that funnel through the Santa Ana river valley south of the San Gabriel and San Bernadino Mountains in southern California, including the Los Angeles basin
payload	The instruments that are accommodated on a spacecraft.
mollweide projection	Map projection system that tries to present more accurate representations of area
interbasin transfer	The physical transfer of water from one watershed to another.
terrace	An elevated surface above the existing level of a floodplain or shore that is created by stream or ocean wave erosion.
hexadecimal	A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F)
dip	One of the directional properties of a geologic structure such as a fold or a fault
indian summer	A period of abnormally warm weather in mid to late autumn with clear skies and cool nights
peak gust	In United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day
scattering	The process in which a beam of light is diffused or deflected by collisions with particles suspended in the atmosphere.
cirque glacier	Small glacier that just occupies a cirque.
mountain breeze	Local thermal circulation pattern found in areas of topographic relief
oil	Hydrocarbon based liquid commonly found in the pores of sedimentary rocks of marine origin.
flood warning	This warning signifies a longer duration and more gradual flooding of counties, communities, streams, or urban areas
community boundary	Spatial edge of a unique community.
tetrahedron	Silicon atom joined by four oxygen atoms (SiO4)
tea	transverse-excited atmospheric pressure
latitude	The location north or south in reference to the equator, which is designated at zero (0) degrees
wind rose	A diagram that shows the percent of time that the wind blows from different directions at a given location over a given time.
cryostatic pressure	Pressure exerted on a substance by ice at rest.
fujita tornado scale	Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed, plus a hypothetical F6 with winds from 318 mph to Mach 1
straight-line winds	Any surface wind that is not associated with rotation
nephelococcygia	A term applied when people find familiar objects within the shape of a cloud.
time	Measurable period in which cause and effect occurs and systems function.
vad	Velocity Azimuth Display
periodic table	Table that describes some of the chemical properties of the known elements.
field capacity	The amount of water held in soil against the pull of gravity.
deuterium	Isotope of hydrogen, with a nucleus containing one proton and one neutron, and an atomic mass number of 2.
insect	Relatively small and simple animals that have a rigid external skeleton, three body sections, three pairs of legs, and antennae
electromagnetic spectrum	See spectrum.
resolution	The smallest change in the environment that causes detectable change in the indication of an instrument
arctic air	A mass of very cold, dry air that usually originates over the Arctic Ocean north of Canada and Alaska.
cenozoic	Geologic era that occurred from 65 million years ago to today.
telemetry	The transmission of data collected at a remote location over communications channels to a central station.
watershed	Land area from which water drains toward a common watercourse in a natural basin
halo	Rings or arcs that encircle the sun or moon when seen through an ice crystal cloud or a sky filled with falling ice crystals
establishment	Subsequent growth and/or reproduction of a colonized species in a new territory.
mariners 1-2-3 rule	A method of avoiding winds associated with a tropical cyclone by taking into account the forecast track error of the National Weather Service over a 10 year period which is approximately 100 nm in 24 hours, 200 nm for 48 hours, and 300 nm in 72 hours
wet-bulb thermometer	Thermometer on a psychrometer that has a moisten wick on its reservoir bulb
altocumulus castellanus	A middle cloud with vertical development that forms from altocumulus clouds
general measurement strategy	An approach to collecting useful information to help the Science Team fulfill the project mission.
dog days	The name given to the very hot summer weather that may persists for four to six weeks between mid-July through early September in the United States
weight barograph	A recording weight barometer.
corona	A pastel halo around the moon or sun created by the diffraction of water droplets
cytoplasm	All of the protoplasm in a cell except for what is contained in the nucleus.
heartwood	the wood at the center of a tree that no longer carrys nutrients through the tree
exploitation	Form of competition where the indirect effects of the two or more species or individuals reduce the supply of the limiting resource or resources needed for survival.
comma echo	A thunderstorm radar echo which has a comma-like shape
frost bite	frozen body tissue.
hydrologic service area	A geographical area assigned to Weather Forecast Office's that embraces one or more rivers.
telemeteorograph	Any meteorological instrument, such as a radiosonde, in which the recording apparatus is located at some distance from the measuring apparatus.
personal equation	A systematic observational error due to the characteristics of the observer
trace	A precipitation amount of less than 0.005 inches
hydrologic model	A conceptual or physically-based procedure for numerically simulating a process or processes which occur in a watershed.
tsunami	An ocean wave produced by a sub-marine earthquake, landslide, or volcanic eruption
independent variable	Variable in a statistical test that is thought to be controlling through cause and effect the value of observations in another dependent variable modeled in the test.
talus	An accumulation of angular rock debris from rockfalls.
gustnado	Slang for a gust front tornado
cumulus fractus	Cumulus clouds that appear in irregular fragments, as if they had been shred or torn
gram calorie	See calorie.
bird	Group of warm blooded vertebrate animals whose body is covered with feathers.
chlorophyll	Green pigment found in plants and some bacteria used to capture the energy in light through photosynthesis.
newton	The unit of force giving a mass of about one kilogram (2.205 pounds) an acceleration of about one meter (1 yard) per second per second.
varve	A thin yearly deposit of sediment found on the bottom of a lake
shear	Its just a variation in the wind speed and/or direction over a short distance.
sectorized hybrid scan	A single reflectivity scan composed of data from the lowest four elevation scans
interface	The point (physical and/or electrical) where two distinct data processing elements meet.
volcanic pipe	A dyke reaches the surface of the Earth
warm front	A transition zone in the atmosphere where an advancing warm air mass displaces a cold air mass.
frontogenesis	The birth or creation of a front
genetic adaptation	Changes in the genetic makeup of organisms of a species due to mutations that allow the species to reproduce and gain a competitive advantage under changed environmental conditions.
beta particle	Electron emitted from the nucleus of a radioactive isotope
icicle	Ice that forms in the shape of a narrow cone hanging point down
din	An acronym for Deutsche Industrial Norm
multicell storm	A thunderstorm made up of two or more single-cell storms.
pressure gradient	The rate of decrease of pressure per unit distance at a fixed time.
population crash	Sudden decline in the number of individuals found in a population because of a scarcity of environmental resources that are required for survival, growth, and reproduction.
ground water	Water within the earth that supplies wells and springs; water in the zone of saturation where all openings in rocks and soil are filled, the upper surface of which forms the water table
kilogram calorie	See calorie.
line of sight	Usually refers to contributions of radiation from the atmosphere along the line-of-sight (path) that an instrument receives.
heliograph	An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine by the action of the sun's rays upon blueprint paper
visibility	The greatest distance an observer can see and identify prominent objects.
apogee	The farthest distance between the moon and earth or the earth and sun.
sand wedge	A form of ice wedge that contains accumulations of wind blown sand in long vertical layers
ice fog	Occurs when the temperature is much below freezing and water vapor condenses directly as ice crystals (sublimation)
open sea	That part of the ocean that extends from the continental shelf
isotach	A line on a weather map connecting points of equal wind speed.
orbital plane	An imaginary gigantic flat plate containing an Earth satellite's orbit
thermal lows	Areas of low pressure that are shallow in vertical extent and are produced primarily by warm surface temperatures.
mb	An acronym for millibars.
tdrss	See Tracking and Data Relay Satellite System.
regulatory floodway	Some maps show an area where construction regulations require special provisions to account for this extra hazard
deposition nuclei	Six-sided microscopic particle that allows for deposition of water as ice crystals in the atmosphere
movement	A term used in geography that deals with the migration, transport, communication, and interaction of natural and human-made phenomena across the spatial dimension.
radiator	Any source of radiant energy, especially electromagnetic energy.
carbonation	Is a form of chemical weathering where carbonate and bicarbonate ions react with minerals that contain calcium, magnesium, potassium, and sodium.
ocean floor	Flat plain found at the bottom of the ocean
variance	A measure of variability.
clear skies	Skies are clear when no clouds or obscurations are observed or detected from the point of observation.
strike-slip fault	Fault that primarily displays horizontal displacement.
mesa	A flat topped hill that rises sharply above the surrounding landscape
torricelli's tube	An early and once universal name for the mercury barometer.
drainage network	System of interconnected stream channels found in a drainage basin.
outgassing	The release of gas from cooling molten rock or the interior of the Earth
maritime effect	The effect that large ocean bodies have on the climate of locations or regions
benthos	The plant and animal organisms that live on the sea floor
stream long profile	Vertical and horizontal profile of the stream
fog	A visible aggregate of minute water droplets suspended in the atmosphere at or near the surface of the earth, reducing horizontal visibility to less than 5/8 statute miles
backscattered radiation	The scattering of radiant energy into the hemisphere of space bounded by a plane normal to the direction of the incident radiation and lying on the same side as the incident ray.
litter	Accumulation of leaves, twigs and other forms of organic matter on the soil surface
continental effect	The effect that continental surfaces have on the climate of locations or regions
base flood	The national standard for floodplain management is the base, or one percent chance flood
pyranograph	An instrument for recording global solar radiation.
protocol	A set of rules or conventions used to standardize data transfer between devices.
saturation	Atmospheric condition where water is changing its phase to liquid or solid
backing	A change in wind direction in a counterclockwise sense; opposite of veering.
distance to target ratio	"Indicates the diameter of the surface area an infrared thermometer will measure at a given distance
inferential statistics	Statistical test that makes generalizations about a population based of the numeric information obtained from a sample based on the laws of probability.
heat advisory	This product is issued by the National Weather Service when excessive heat may pose a hazard or is life threatening if action is not taken
estuary	The thin zone along a coastline where freshwater systems and rivers meet and mix with a salty ocean (such as a bay, mouth of a river, salt marsh, lagoon).
haze	A concentration of salt particles or other dry particles not readily classified as dust or other phenomenon
subsurface storm flow	The lateral motion of water through the upper layers until it enters a stream channel
radiosonde observation	An evaluation of upper air temperature, pressure, and humidity from radio signals received from a balloon-borne radiosonde.
photosynthetic autotroph	An organism that produces food molecules inorganically by using light and the chemical process of photosynthesis
aoa	An acronym for "At or Above".
monsoon	The seasonal shift of winds created by the great annual temperature variation that occurs over large land areas in contrast with associated ocean surfaces
twister	In the United States, a colloquial terms for a tornado.
cloud deck	The top of a cloud layer, usually viewed from an aircraft.
pore pressure	The interstitial pressure of water within a mass of soil, rock, or concrete.
stream load	Refers to the material or sediment carried by a stream
radiative transfer	Theory dealing with the propagation of electromagnetic radiation throuqh a medium.
carbon dioxide flux	The rate of flow for carbon dioxide, a heavy, colorless greenhouse gas.
magnetic field	The space influence by magnetic force
climate	It describes the average weather conditions in a certain place or during a certain season
bathythermograph	A device used to obtain a record of temperature against depth (pressure) in the ocean
synchro	A motorlike device containing a rotor and a stator and capable of converting an angular position into an electrical signal, or an electrical signal into an angular position
radar	Precipitation often totally envelops the region of rotation, making visual identification of any embedded tornadoes difficult and very dangerous.
condensation funnel	A funnel-shaped cloud consisting of condensed water drops that has possible rotation.
gleization	A soil formation process that occurs in poorly drained environments
mountain breeze	A katabatic wind, it is formed at night by the radiational cooling along mountainsides
cellular	Composed of cells
ozone	Tri-atomic oxygen that exists in the Earth's atmosphere as a gas
backscatter	A radar echo that is reflected, or scattered, at 180 degrees to the direction of the incident wave
extinction	The attenuation of light.
bandwidth	The total range of frequency required to pass a specific modulated signal without distortion or loss of data
cambrian explosion	Great diversification of multicellular life forms in the Earth's oceans that started during the Cambrian about 570 million years ago.
coriolis effect	The effect caused by the Earth's rotation which deflects air moving between two places
ccl	An acronym for Convective Condensation Level.
channelization	The modification of a natural river channel; may include deepening, widening, or straightening.
normal	The long-term average value of a meteorological element for a certain area
middle latitudes	The latitude belt roughly between 35 and 65 degrees North and South
straight-line hodograph	The name pretty well describes what it looks like on the hodograph
lapse rate	The rate of change of an atmospheric variable, usually temperature, with height
haccp	An acronym for Hazard Analysis Critical Control Point
shear wave	A seismic wave that creates wave-like motion perpendicular to the direction of seismic energy propagation
air	Relative Humidity-The ratio of the air's water vapor content to its water water vapor capacity.
isotherm	A line on a weather map connecting points of equal temperature.
snow squalls	brief, intense snow showers, accompanied by strong, gusty winds
flood crest	the highest height that the river reaches during a flood event
vapor trail	A cloudlike streamer or trail often seen behind aircraft flying in clear, cold, humid air
soil solution	Aqueous liquid found within a soil
longitude	The angular distance from the Greenwich meridian (0 degrees), along the equator
circuit	The complete path of an electric current; an assemblage of electronic elements; a means of two-way communication between two points - comprised of associated "go" and "return" channels.
effusive eruption	Volcanic eruption where low-viscosity basaltic magma is released
response time	The length of time a given instrument requires to reach a specified percentage of its final reading value
standing wave	An atmospheric wave that is stationary with respect to the medium in which it is embedded.
landsat	Series of satellites launched by NASA for the purpose of remotely monitoring resources on the Earth
clinometer	An instrument used to measure angles of inclination
deep seepage	Infiltration which reaches the water table.
photodissociation	The splitting of a molecule by photon normally from the Sun.
siberian high	The semi-permanent high pressure area that forms over Siberia during the winter
thunder	The sound emitted by rapidly expanding gases along the channel of a lightning discharge
cheyenne fog	An upslope fog formed by the westward flow of air from the Missouri River Valley, producing fog on the eastern slopes of the Rockies.
subsidence	Lowering or sinking of the Earth's surface.
temperature	Specific Humidity In a system of moist air, the ratio of the mass of water vapor to the total mass of the system.
gravitational water	Water that moves through soil due to gravitational forces
guided wave	Electromagnetc or acoustic wave that is constrained within certain boundaries, as in a wave guide (transmission line).
pixel	Smallest par (addressable element) of an electronically-coded image, such as a computer display
depletion curve	That part of the hydrograph extending from the point of termination of the Recession Curve to the subsequent rise or alternation of inflow due to additional water becoming available for stream flow.
osha	Occupational Safety and Health Administration
centripetal force	The force required to keep an object moving in a curved or circular path
fossil	Geologically preserved remains of an organism that lived in the past.
tropical weather summary	The National Hurricane Center issues a monthly summary of tropical weather is included at the end of the month or as soon as feasible thereafter, to describe briefly the past activity or lack thereof and the reasons why.
matter	Is the material (atoms and molecules) that constructs things on the Earth and in the Universe.
subpolar glacier	Glacier in which the ice found from the its surface to base has a temperature as cold as -30° Celsius throughout the year
noctiphobia	The fear of the night.
ria coast	An extensively carved out coast with conspicuous headlands and deep re-entrants.
refraction	The bending of light as it passes from one medium to another.
seismograph	Instrument that measures the energy contained in seismic waves from an earthquake or other type of ground displacement.
laterite	Hard subsurface deposit of oxides of aluminum and iron found in tropical soils where the water table fluctuates with seasonal changes in precipitation.
campbell-stokes recorder	A sunshine recorder of the type in which the time scale is supplied by the motion of the sun
nivation	Process where snow patches initiate erosion through physical weathering, meltwater flow, and gelifluction.
discharge	See stream discharge.
satellite	A free-flying object that orbits the Earth, another planet, or the sun.
meter-ton-second system	A system of physical units based upon the use of the meter, the metric ton (106 grams), and the second as elementary quantities of length, mass, and time, respectively.
end block	a piece of hardwood that supports the sides (or ribs) of the instrument where they join and provides a structural entity for the end pin of the instrument.
data buoys	Buoys placed throughout the Gulf of Mexico and along the Atlantic and Pacific coasts of the United States that relay information on air and water temperature, wind speed, air pressure, and wave conditions via radio signals.
friction	Resistance between the contact surfaces of two bodies in motion.
secondary carnivore	See tertiary consumer.
downdraft	A relatively small-scale, downward moving current of air.
abutment	The part of a valley or canyon wall against which a dam is constructed
ultraviolet radiation	Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).
protein	Organic substances primarily composed of carbon, hydrogen, nitrogen, and some other minor elements which are arranged in about 20 different compounds known as amino acids
binary	A numbering system using a base number of 2 and having only two digits: 0 and 1
coriolis force	A fictitious force used to account for the apparent deflection of a body in motion with respect to the earth, as seen by an observer on the earth
backing wind	A wind that changes its direction in a counter clockwise motion
altimeter	An instrument used to determine the altitude of an object with respect to a fixed level
folding	Aliasing; applied to both velocity and range aliasing.
ocean	A body of saline water found occupying all or part of the Earth's ocean basins
tidal piling	Abnormally high water levels caused by the accumulation of successive incoming tides that do not completely drain due to opposing strong winds and/or waves.
cup anemometer	Anemometer which measures wind speed by the speed of rotation of 3 or 4 hemispherical or conical cups, each fixed to the end of a horizontal arm projecting from a vertical axis
topography	Generally, the lay-out of the major natural and man-made physical features of the earth's surface
degradation	Readjustment of the stream profile where the stream channel is lowered by the erosion of the stream bed
vortex	In its most general use, any flow possessing vorticity
sea-level pressure	Average atmospheric pressure at sea-level
carry-over	The portion of the streamflow during any month or year derived from precipitation in previous months or years.
ffg	An acronym for Flash Flood Guidance.
isohel	A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.
humidity	Water in the air.
modulation	The process of modifying some characteristic of a wave (the carrier) so that it varies in step with the instantaneous value of another wave (the modulating wave) in order to transmit a message
shefpars	A software decoder for SHEF Data.
cistern barometer	A mercury barometer in which the lower mercury surface is larger in area than the upper surface
plastic deformation	Irreversible change in the shape of a material without fracture as the result of the force of compression or expansion.
frontal lifting	Lifting of a warmer or less dense air mass by a colder or more dense air mass at a frontal transitional zone.
air pollution	The existence in the air of substances in concentrations that are determined unacceptable to human health and the environment
polygenetic landform	Landform that shows the influence of two or more major geomorphic processes
paternoster lakes	A linear series of mountain valley lakes that are formed from glacial erosion
range	The interval between the lower and upper measuring limits of an instrument, i.e
mean temperature	The average temperature of the air as indicated by a properly exposed thermometer for a given time period, usually a day, a month, or a year.
cloud ice water	The concentration (mass/vol) of ice water particles in a cloud.
ebcdic	Extended Binary Coded Decimal Interchange Code
evapotranspiration	The combined processes by which water is transferred from the earth's surface to the atmosphere: evaporation of liquid or solid water plus transpiration from plants.
dew	Condensation of water on the Earth's surface because of atmospheric cooling.
base	A substance that forms a salt when it reacts with acid
breach	The failed opening in a dam.
tributary	A smaller branching stream channel that flows into a main stream channel
breakup jam	Ice jam that occurs as a result of the accumulation of broken ice pieces.
ldc	See less developed country.
response time	The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.
radiance	In radiometry, a measure of the intrinsic radiant intensity emitted by a radiator in a given direction.
minor flooding	A general term indicating minimal or no property damage but possibly some public inconvenience.
vdt	Video Display Terminal
foot-pound	A unit of energy equal to 1.356 joules.
cold wave	A rapid fall in temperature within twenty-four hours to temperatures requiring substantially increased protection to agriculture, industry, commerce, and social activities
alberta clipper	A fast moving, snow-producing weather system that originates in the lee of the Canadian Rockies
station pressure	The atmospheric pressure with respect to the station elevation.
evapotranspiration	The vaporization of water through direct evaporation from wet surfaces and the release of water vapor by vegetation.
convective condensation level	The height at which a parcel of air, if heated sufficiently from below, will rise adiabatically until it is just saturated.
word	A fixed-length group of bits representing the largest data element handled as a unit by a computer
decibel	A tenth of a bel
landfall	The point at which a tropical cyclone's eye first crosses a land mass.
gaging station	A particular site on a river, stream, canal, or body of water where systematic observations of stage and/or flow are measured.
land breeze	A wind that blows from the land towards a body of water
hydrologic unit	A geographical area representing part or all of a surface drainage basin or distinct hydrologic feature such as a reservoir, lake, etc.
elastic wave	An energy wave that causes elastic deformation in a material without its structure and shape being deformed.
solar cycle	Eleven-year cycle of sunspots and solar flares that affects other solar indexes such as the solar output of ultraviolet radiation and the solar wind
magnetosphere	Region surrounding a celestial body where its magnetic field controls the motions of charged particles
tundra	High latitude biome dominated by a few species of dwarf shrubs, a few grasses, sedges, lichens, and mosses
high	A digital logic state corresponding to a binary "l" See low.
celsius temperature scale	International thermometric scale on which the freezing point of water equals 0° and the boiling point equals 100° at standard atmospheric pressure (760 mm Hg)
vapor pressure	at which the gas is called saturated at the current temperature, expressed as a percentage.
blocking high	The development of a warm ridge or cutoff high aloft at high latitudes which becomes associated with a cold high at the surface, causing a split in the westerly winds
geography	The study natural and human constructed phenomena relative to a spatial dimension.
hummock	A hillock of broken ice which has been forced upward by pressure.
gas	A state of matter where molecules are free to move in any direction they like
permafrost	a soil layer below the surface of tundra regions that remains frozen permanently
potential evapotranspiration	Is a measure of the ability of the atmosphere to remove water from the surface through the processes of evaporation and transpiration assuming no limitation on water supply.
evaporation	The process by which a liquid is transformed to a vapor
latitude	Latitude is a north-south measurement of position on the Earth
mean	Statistical measure of central tendency in a set of data
radiant-energy thermometer	An instrument which determines the black-body temperature of a substance by measuring its thermal radiation.
tornado	A violently rotating column of air in contact with and extending between a convective cloud and the surface of the earth
fault plane	The plane that represents the fracture surface of a fault.
convection	Convection involves the transfer of heat energy by means of vertical mass motions through a medium.
cumulonimbus mammatus	A portion of a cumulonimbus cloud that appears as a pouch or udder on the under surface of the cloud
engineering change request	A method of formally requesting that a change be made to the infrastructure
transmissometer	An electronic instrument system which provides a continuous record of the atmospheric transmission between two fixed points
forecast crest	The highest elevation of river level, or stage, expected during a specified storm event.
fossil fuel	Carbon based remains of organic matter that has been geologically transformed into coal, oil and natural gas
hypothesis testing	Process where an alternative and a null hypothesis are statistically tested for the purpose of falsifying a hypothesis.
rossby waves	A series of troughs and ridges on quasi-horizontal surfaces in the major belt of upper tropospheric westerlies
desertification	Conversion of marginal rangeland or cropland to a more desert like land type
thermal shift	The change in the measured transducer output caused by changes in ambient temperature
british thermal unit	A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit
breakup period	The period of disintegration of an ice cover.
sulfuric acid	Acid with the chemical formula H2SO4.
gyre	A circular or spiral motion, primarily referring to water currents.
regosol soil	Soil order (type) of the Canadian System of Soil Classification
herbivore	Heterotrophic organism that consumes plants for nutrition
basement rock	Very old granite and metamorphic rocks found in continental crust
precision	See resolution.
latent heat flux	The time rate of flow for the specific enthalpy difference between two phases of a substance at the same temperature, typically water.
geosphere	Considered the solid portions of the earth, including the hydrosphere and the lithosphere, as opposed to the atmosphere, which lies above it
wind speed	Rate of wind movement in distance per unit time.
rain	drizzle, hail, snow and sleet
hydrosphere	The water portion of the earth as distinguished from the solid part, called the lithosphere, and from the gaseous outer envelope, called the atmosphere.
microwave radiation	Form of electromagnetic radiation with a wavelength between 0.1 to 100 centimeters.
direct insolation	The solar radiation that is transmitted directly through the atmosphere to the earth's surface without interacting with atmospheric components.
modem	A device that allows a terminal or computer at one location to communicate with a terminal or computer at a distant location via wire or phone lines.
mesolow	A small scale low pressure center, ranging from the size of an individual thunderstorm to many tens of miles.
snow garland	Snow appearing as a beautiful long thick rope draped on trees, fences and other objects
visibility	A measure of the opacity of the atmosphere, and therefore, the greatest distance one can see prominent objects with normal eyesight
wind rose	A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.
leachate	Solution containing material leached from a soil.
mycorrhizae	Mutualistic association of a fungus with the root of higher plant
viscosity	The amount of the resistance to flow in a fluid due to intermolecular friction.
correlation	A measure of the similarity between variables or functions.
downward total radiation	Solar and terrestrial radiation directed downwards (towards the earth's surface); incoming radiation.
helical flow	Movement of water within a stream that occurs as spiral flows.
abyssal plain	The flat, gently sloping or nearly level region of the sea floor.
toe drain	A drain which carries seepage away from the dam and can allow seepage quantities to be measured.
humidity	Relative humidityIs a traditional indicator of the air's moisture content
pressure altitude	The altitude in standard atmosphere at which a given pressure will be observed
exogenic	Refers to a system that is external to the Earth.
altimeter setting	The pressure value to which an aircraft altimeter scale is set so that it will indicate the altitude above mean sea level of an aircraft on the ground at the location for which the value was determined.
cumulonimbus	A giant thundercloud that towers to gray heights
chronograph	A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.
frost creep	Slow mass movement of soil downslope that is initiated by freeze-thaw action
air quality standards	The maximum level which will be permitted for a given pollutant
surface wave	Type of seismic wave that travels across the Earth's surface
resistance	The resistance to the flow of electric current measured in ohms
sea mile	A unit of length distinguished from a nautical mile
water consumption	The complete removal of water from some type of source, like groundwater, for some use by humans
robinson projection	Map projection system that tries to present more accurate representations of area
satellite positioning	A procedure by which satellites are used to locate precise objects or particular points on Earth
interglacial	Period of time during an ice age when glaciers retreated because of milder temperatures.
indian summer	An unseasonably warm period near the middle of autumn, usually following a substantial period of cool weather.
river stage	See stage.
earth system	The Earth regarded as a unified system of interacting components, including geosphere (land), atmosphere (air), hydrosphere (water and ice), and biosphere (life).
bolometer	Instrument for measuring the intensity of radiant energy
third law of thermodynamics	This law states if all the thermal motion of molecules (kinetic energy) could be removed, a state called absolute zero would result and all energy would be randomly distributed.
meteorology	The study of the atmosphere and atmospheric phenomena.
sediment rating curve	Numerical expression or graphical curve that describes the quantitative relationship between stream discharge and the sediment transported by a particular stream.
stream discharge	A river or stream's rate of flow over a particular period of time
goniometer	An instrument used for measuring geometric angles
frequency	Number of cycles and parts of cycles completed per second
isohaline	A line (or surface) connecting points of equal or constant salinity in water bodies or groundwater.
seepage lake	A lake that gets its water primarily from the seepage of groundwater.
food web	A model describing the organisms found in a food chain
orogenesis	The process of mountain building through tectonic forces of compression and volcanism.
ionosphere	A region in the atmosphere above 50 kilometers from the surface where relatively large concentrations of ions and free electrons exist
ice storm	A severe weather condition characterized by falling freezing precipitation
head race	A channel which directs water to a water wheel; a forebay.
upwind	In the direction from which the wind is blowing.
wave	An identifiable, periodic disturbance or motion in a medium that shows displacement
mid-oceanic ridge	Chain of submarine mountains where oceanic crust is created from rising magma plumes and volcanic activity
magnetic south	See South Magnetic Pole.
geomorphology	The field of knowledge that investigates the origin of landforms on the Earth and other planets.
graben fault	This fault is produced when tensional stresses result in the subsidence of a block of rock
t rolls	Slang term for transverse rolls.
precipitate	Solidification of a previously dissolved substance from a solution.
headlands	A strip of land that juts seaward from the coastline
inland freshwater wetlands	Swamps, marshes, and bogs found inland beyond the coastal saltwater wetlands.
non-parametric statistical test	Statistical tests that do not assume the sample data is normally distributed.
temperature	pressure,and humidity throughout
dendritic	Term used to describe the stream channel pattern that is completely random
static pressure vent	A vent used with pressure sensors to reduce the effect of wind on the pressure inlet
atmospheric pressure	The pressure asserted by the mass of the column of air directly above any specific point (also called air pressure or barometric pressure).
prognostic chart	A chart of forecast predictions that may include pressure, fronts
spring	An issue of water from the earth; a natural fountain; a source of a reservoir of water.
upwelling	The process by which water rises from a lower to a higher depth, usually as a result of divergence and offshore currents
maritime air mass	An air mass influenced by the sea
centrifugal force	A force directed outward, away from the center of a rotating object; equal in magnitude to the centripetal force but in the opposite direction.
nitrous oxide	Gas found in the atmosphere that contributes to the greenhouse effect
shower	Precipitation from a cumuliform cloud
eukaryota	All the organisms with a eukaryote cell type
freezing level	Lowest altitude in the atmosphere over a given location at which the air temperature is 0°C.
porosity	The void spaces found in rock, sediment, or soil
hydrograph	A graphical representation of stage or discharge at a point on a stream as a function of time.
wave staff	Same as wave pole.
prt	An acronym for Platinum Resistance Thermometer
sand sheet	Deposit of sometimes stratified less well sorted sand that almost resemble dunes
mesoscale	A scale of meteorological phenomena that ranges in size from a few km to about 100 kilometers
acid rain	Acids form when certain atmospheric gases (primarily carbon dioxide, sulfur dioxide, and nitrogen oxides) come in contact with water in the atmosphere or on the ground and are chemically converted to acidic substances
symbiotic	Mutual relationship between two organisms which is necessary for either to survive.
cloudburst	A sudden, heavy rainfall of a showery nature.
grassland	Ecosystem whose dominant species are various types of grass
jet	A fast-moving wind current surrounded by slower moving air.
t. d.	An acronym for Tropical Depression.
actual evapotranspiration	The rate of water lost from vegetation and soil, ordinarily at a slower rate than the potential rate.
counterradiation	The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface
bellows	See aneroid capsule.
flash multiplicity	The number of return strokes in a lightning flash.
nitric acid	Acid with the chemical formula: HNO3.
dryline punch	A surge of drier air; normally a synoptic-scale or mesoscale process
phase change	Reorganization of a substance at the atomic or molecular level resulting in a change of the physical state of matter
valley fog	Fog formed by the movement of cooler, more dense air from higher elevations to the warm valley bottom.
trmm	See Tropical Rainfall Measuring Mission.
drumlin	A hill shaped deposit of till
sidereal day	Time it takes to complete one Earth rotation relative to the position of a fixed star
climax community	Plant community that no longer undergoes changes in species composition due to succession.
centigrade	A temperature scale based on 100 degrees of difference between the freezing and boiling points of water
isohume	A line drawn through points of equal humidity on a given surface.
subtropical air	An air mass that forms over the subtropical region
hygrometer	An instrument that measures the water vapor content of air or the humidity.
pressure change	The net difference between the barometric pressure at the beginning and ending of a specified interval of time, usually the three hour period preceding an observation.
elastic deformation	Change in the shape of a material as the result of the force of compression or expansion
erg desert	A region in a desert where sand is very abundant.
perched water table	Water table that is positioned above the normal water table for an area because of the presence of a impermeable rock layer.
overland flow	The flow of rainwater or snowmelt over the land surface toward stream channels
continental plate	A rigid, independent segment of the lithosphere composed of mainly granite that floats on the viscous plastic asthenosphere and moves over the surface of the Earth
slip-face	The lee side of a dune where material accumulates and slides or rolls downslope.
friction head	The decrease in total head caused by friction.
temperate climate	Climates with distinct winter and summer seasons, typical of regions found between the Tropics of Cancer and Capricorn and the Arctic and Antarctic Circles
scintillometer	A type of photoelectric photometer used to measure high-altitude winds on the assumption that stellar scintillation is caused by atmospheric inhomogeneities being carried along by wind near the tropopause level.
gms	See Geostationary Meteorological Satellite.
classic supercell	See supercell.
salinity	Concentration of dissolved salts found in a sample of water
stable/stability	Occurs when a rising air parcel becomes denser than the surrounding air
cyclone	Area of low pressure in the atmosphere that displays circular inward movement of air
diurnal	Means daily, especially pertaining to actions which are completed in 24 hours and are repeated every 24 hours.
nonlinear	Not a linear function of the relevant variables.
desert pavement	A veneer of coarse particles left on the ground after the erosion of finer particles by wind.
underflow	The lateral motion of water through the upper layers until it enters a stream channel
centripetal force	Force required to keep an object moving in a circular pattern around a center of rotation
klystron	An electron tube used as a low-power oscillator or a high-power amplifier at ultrahigh frequencies
hysteresis	The maximum difference in output for any given input (within the specified range) when the value is approached first with increasing, and then with decreasing, input signals
tectonics	See plate tectonics.
humidity	A general term used to describe the amount of water vapor found in the atmosphere.
acid rain	Cloud or rain droplets containing pollutants, such as oxides of sulfur and nitrogen, to make them acidic.
prokaryote	Organisms whose cells have their genetic material in the form of loose strands of DNA found in the cytoplasm
poles/polar	The poles are the geographic point at 90 degrees latitude North and South on the earth's surface
haze	Tiny particles of dust, smoke, salt or pollution droplets that are scattered through the air
scud	Ragged low clouds, usually stratus fractus
thermocline	Boundary in a body of water where the greatest vertical change in temperature occurs
dense fog	Its fog that reduces horizontal visibility to 1/4 mile or less
salt water	The water of the ocean, distinguished from fresh water by its appreciable salinity.
cold air funnel	Funnel clouds, usually short-lived, that develop from relatively small showers or thunderstorms when the air aloft is very in cold
basin recharge	Rainfall that adds to the residual moisture of the basin in order to help recharge the water deficit
altostratus	It is a bluish veil or layer of clouds having a fibrous appearance
dew	Condensation in the form of small water drops that forms on grass and other small objects near the ground when the temperature has fallen to the dew point, generally during the nighttime hours.
electrolytic strip	Same as humidity strip.
reservoir	A manmade facility for the storage, regulation and controlled release of water.
laminates	materials in which thin sheets of wood are glued together (with each layer’s grain direction perpendicular to the last) to make a durable, rigid, composite, wooden sheets
rate-of-rainfall gauge	Same as rain-intensity gauge.
theta-e ridge	An axis of relatively high values of theta-e
atmosphere	The gaseous envelope surrounding the earth, composed primarily of nitrogen and oxygen.
hygroscopic	Substances that have the ability to absorb water and therefore accelerate the condensation process.
standard atmosphere	A standard atmosphere has been defined by the International Civil Aeronautical Organization (ICAO)
dovetail	an interlocking joint that combines a flaring tenon and a mortise into which it tightly fits– the neck joints on Martin’s Standard Series guitars are dovetail joints.
snow flurries	They are intermittent light snowfalls of short duration (generally light snow showers) with no measurable accumulation.
net radiation	The difference between downward and upward (total) radiation; net flux of all radiation.
climate prediction center	The CPC is one of nine national centers that comprises the National Centers for Environmental Prediction (NCEP)
mutualism	Interspecific interaction where both species experience and increase in their fitness after interacting with the other species
dry deposition	The transport of gases and minute liquid and solid particles from the atmosphere to the ground surface without the aid of precipitation or fog
temperature	to the maximum amount which could exist at that temperature
nadir	The point on any given observer's celestial sphere diametrically opposite of one's zenith.
pressure	winds) at a given time.
rockfall	Type of mass movement that involves the detachment and movement of a small block of rock from a cliff face to its base
heat lightning	There is no such thing as heat lightning
dropsonde	A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.
paleoclimatology	Scientific study of the Earth's climate during the past.
radiant energy	Energy in the form of electromagnetic waves and photons
gallery	A passageway within the body of a dam or abutment.
twister	A slang term used in the United States for a tornado.
sheeting	A form of physical weathering of rock where surface sheets of material fracture and exfoliate because of pressure release
levee	A long, narrow embankment usually built to protect land from flooding
data quality report	Used to identify and document problems with ARM systems, physical infrastructure, or instruments.
conductivity	A unit measure of electrical conduction
apogee	The point farthest from the earth on the moon's orbit
protozoa	Heterotrophic eukaryotic unicellular organisms that belong to the kingdom protista.
competition	Interaction where two or more organisms in the same space require the same resource (e.g., food, water, nesting space, and ground space) which is in limiting supply to the individuals seeking it
sublimation	The process of a solid (ice) changing directly into a gas (water vapor), or water vapor changing directly into ice, at the same temperature, without ever going through the liquid state (water).
conduction	The transfer of heat through a substance by molecular action or from one substance by being in contact with another.
heat exhaustion	The effect of excessive heat, particularly when combined with high humidity, on a human being
forebay	The water behind (upstream) of the dam.
unit hydrograph duration	The time over which one inch of surface runoff is distributed for unit hydrograph theory.
outer convective bands	These bands occur in advance of main rain shield and up to 300 miles from the eye of the hurricane
vector	Any quantity, such as force velocity, or acceleration, which has both magnitude and direction at each point in space, as opposed to scalar which has magnitude only
sleet	Describes solid grains of ice formed by the freezing of raindrops or the refreezing of largely melted snowflakes
organic matter	Mass of matter that contains living organisms or non-living material derived from organisms
track	The path that a storm or weather system follows.
evaporation	The physical process by which a liquid, such as water is transformed into a gaseous state, such as water vapor
basic	Substance having a pH greater than 7.
luthier	Someone who builds acoustic stringed instruments such as violins, guitars, etc. Also, the word luthier is sometimes used in reference to someone who has advanced repair/restoration skills on acoustic stringed instruments.
ecosystem	Any natural unit or entity including living and non-living parts that interact to produce a stable system through cyclic exchange of materials.
pressure	The force exerted by the weight of the atmosphere, also known as atmospheric pressure
zodiac	The position of the sun during the course of the year as it appears to move though successive constellations
snow flurry	Snow shower, particularly of a very light and brief nature.
ph	Scale used to measure the alkalinity or acidity of a substance through the determination of the concentration of hydrogen ions in solution
humidity	The amount of water vapor in the air.
region	A term used in geography that describes an area of the Earth where some natural or human-made phenomena display similar traits.
neutral solution	Any water solution that is neutral (pH approximately 7) or has an equal quantity of hydrogen ions (H+) than hydroxide ions (OH-)
penetrometer	A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil
canopy	The layer formed naturally by the leaves and branches of trees and plants.
aerosol concentration	Number of aerosols per unit volume.
circulation cells	Large areas of air movement created by the rotation of the earth and the transfer of heat from the equator toward the poles
external instruments	Instruments that belong to organizations that are outside of the ARM Program.
runway visual range	The maximum distance along the runway at which the runway lights are visible to a pilot at touchdown
hydrologic cycle	Model that describes the movement of water between the hydrosphere, lithosphere, atmosphere, and biosphere.
reflection rainbow	A rainbow formed by light rays which have been reflected from an extended water surface
logarithm	Exponent of the power to which it is necessary to raise a fixed number (the base) to produce the given number
carbohydrate	Is an organic compound composed of carbon, oxygen, and hydrogen atoms
cin	An acronym for Convective Inhibition.
big crunch	Collapse of the Universe into its original form before the Big Bang
species association	A particular grouping of species in an area.
u.s. geological survey	The Federal Agency chartered in 1879 by congress to classify public lands, and to examine the geologic structure, mineral resources, and products of the national domain
ice crystal	Precipitation consisting of small, slowly falling crystals of ice.
time-height display	An intensity-modulated display which has height as the vertical coordinate and time as the horizontal coordinate; usually used for vertically-pointing antennas only.
velocity	The speed of movement of an object in one direction.
ecological diversity	See ecosystem diversity.
isallobar	A line of equal change in atmospheric pressure during a specified time period.
population density	Number of individuals of a particular species found in a specified area.
flood	Inundation of a land surface that is not normally submerged by water from quick change in the level of a water body like a lake, stream, or ocean.
savanna	A tropical or sub-tropical plant community characterized by trees and shrubs scattered among a cover of grasses, herbs and forbs
carbon monoxide	A colorless, odorless, and tasteless gas that is produced by the incomplete burning of fossil fuels
heat balance	The equilibrium existing between the radiation received and emitted by a planetary system.
latent heat	The energy released or absorbed during a change of state.
continental glacier	Largest type of glacier with a surface coverage in the order of 5 million square kilometers.
small stream flooding	Flooding of small creeks, streams, or runs.
isolated storm	An individual cell or a group of cells that are identifiable and separate from other cells in a geographic area.
rs232	A standard interface between a computer input/output port and a peripheral device
palouser	A strong, dangerous, katabatic wind that descends from the mountains into the Palouse River valley in northern Idaho and eastern Washington
iso-elastic spring	A spring which is designed to achieve a fixed spring constant over a wide temperature range
face	The external surface of a structure, such as the surface of a dam.
drought	Abnormal dry weather for a specific area that is sufficiently prolonged for the lack of water to cause serious hydrological imbalance.
ribbon lightning	Appears to be a broad stream of fire
pressure jump	A sudden increase in the observed atmospheric pressure or station pressure.
thermometer	An instrument for measuring temperature by utilizing the variation of the physical properties of substances according to their thermal states
beaufort wind scale	A system of estimating and reporting wind speeds
montmorillonite	A type of clay that has a large capacity to shrink and expand with wetting and drying.
dynamics	The study of the action of forces on bodies and the changes in motion they produce.
zonal index	The measure of the strength of the westerly winds of the middle latitudes
electromagnetic radiation	Also called radiation, it is waves of energy propagated though space or through a material media.
mistral	Term used to describe a katabatic wind in southern France.
fitness	A measure of the health of a species in terms of physiology and future reproductive success.
entropy	Entropy is the measure of the disorder or randomness of energy and matter in a system.
bridge	the part of an acoustic instrument that transmits vibration from the strings to the top of the instrument; the bridge can be attached to the soundboard with glue or held against the soundboard by the tension of the strings that pass over it
mole	A unit of mass numerically equal to the molecular weight of the substance
kew-pattern barometer	Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.
zonal flow	The flow of air along a latitudinal component of existing flow, normally from west to east.
tipping-bucket rain gauge	A rain gauge where the precipitation collected by the receiver empties into one side of a chamber which is partioned transversely at its center and is balanced bistably upon a horizontal axis
white rainbow	Same as fogbow.
steppe	Russian term for mid-latitude grasslands.
candela	Unit of luminous intensity
true anomaly	One of six Keplerian elements, it locates a satellite on an orbit
circulation cell	A "package" of air with a distinct circulation pattern, i.e., a lake breeze.
tropical disturbance	An area of organized convection, originating in the tropics and occasionally the subtropics, that maintains its identity for 24 hours or more
organ	Group of cells and tissues that have a particular function for an organism.
bay	A wide area of water extending into land from a sea or lake.
chemical	One of the millions of different elements and compounds found naturally and synthesized by humans.
feeder bands	In tropical parlance, the lines or bands of thunderstorms that spiral into and around the center of a tropical system
chromosome	Organic structure that carries an organism's genetic code (DNA).
firmware	Programs or instructions which are stored in read-only memory.
color temperature	An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.
bank storage	Water absorbed and stored in the void in the soil cover in the bed and banks of a stream, lake, or reservoir, and returned in whole or in part as the level of water body surface falls.
flood	The inundation of a normally dry area caused by high flow, or overflow of water in an established watercourse, such as a river, stream, or drainage ditch; or ponding of water at or near the point where the rain fell
water	land, and ice), kinetic (wind and ocean currents, together with associated vertical motions and the motions of air masses, aqueous humidity, ...
swath	The area observed by a satellite as it orbits the Earth.
turbidity	The thickness or opaqueness of water caused by the suspension of matter
sensor	Device that produces an output (usually electrical) in response to stimulus such as incident radiation
snow core	A sample of either freshly fallen snow, or the combined old and new snow on the ground
diurnal	Performed in twenty-four hours, such as the diurnal revolution of the Earth.
frost point	Dew point below freezing.
livingstone sphere	An clay atmometer consisting of a hollow ceramic sphere through which evaporation occurs
trade winds	Two belts of prevailing winds that blow easterly from the subtropical high pressure centers towards the equatorial trough
source region	Area where air masses originate and come to possess their moisture and temperature characteristics.
fluid drag	Reduction in the flow velocity of a fluid by the frictional effects of a surface.
immigrant species	Species that migrate into an ecosystem or that are deliberately or accidentally introduced into an ecosystem by humans
transport	One of three distinct processes involved in erosion
whiteout	It results from extreme blizzard conditions in which blowing snow or falling snow reduces visibility so that the sky, air, and ground becomes indistinguishable
cell	Convection in the form of a single updraft, downdraft, or updraft/downdraft couplet, typically seen as a vertical dome or tower as in a cumulus or towering cumulus cloud
taxon	A classification category for a group of organisms.
large calorie	See calorie.
radiational cooling	The cooling of the earth's surface and the adjacent air
gelifluction	Form of mass movement in periglacial environment where a permafrost layer exists
obliquity	Tilt of the Earth's polar axis as measured from the perpendicular to the plane of the Earth's orbit around the Sun
hydrography	The study of waters (including oceans, lakes, and rivers) embracing either: (a) their physical characteristics, from the standpoint of the oceanographer or limnologist; or (b) the elements affecting safe navigation, from the point of view of the mariner
time constant	As defined by engineering sciences, a time constant is the actual time that a physical system requires to reach 62.3% of its total value
macroscale	Large scale, characteristic of weather systems several hundred to several thousand kilometers in diameter.
impervious	The ability to repel water, or not let water infiltrate.
isotropic	A line of constant equal physical properties along all axes.
contents	The volume of water in a reservoir
calcium carbonate	Compound consisting of calcium and carbonate
sleet	ice pellets or granules of frozen rain
cutoff low	A closed low which has become completely displaced (cut off) from basic westerly current, and moves independently of that current
mountain barometer	Any conventional barometer fitted with an extended scale so that atmospheric pressure measurements may be made at both high and low altitudes.
potentiometer	An instrument for measuring differences in electric potential.
fetch	The distance of open water in one direction across a body of water over which wind can blow.
pollutant	Particles, gases, or liquid aerosols in the atmosphere which have an undesirable effect on humans or their surroundings
downslope effect	The warming of an air flow as it descends a hill or mountain slope.
weather	The state of the atmosphere, mainly with respect to its effects upon life and human activities
fujita tornado intensity scale	Tornado classification system developed by T
strata	The layers or beds found in sedimentary rock.
vertical wind shear	The rate of change of wind speed or direction, with a given change in height
exotic stream	A stream that has a course that begins in a humid climate and end in an arid climate
map	An abstraction of the real world that is used to depict, analyze, store, and communicate spatially organized information about physical and cultural phenomena.
mesozoic	Geologic era that occurred from 245 to 65 million years ago.
dry slot	A zone of dry (and relatively cloud-free) air which wraps east or northeast into the southern and eastern parts of a synoptic scale or mesoscale low pressure system
clear	To restore a device to a its initial state, usually the zero state.
pulse-time-modulated radiosonde	A radiosonde which transmits the indications of the meteorological sensing elements in the form of pulses spaced in time
seisomograph	An instrument used to measure and record earthquake vibrations and other earth tremors.
anticyclonic rotation	Rotation in the opposite sense as the Earth's rotation
severe thunderstorm	A thunderstorm with winds measuring 50 knots (58 mph) or greater, 3/4 inch hail or larger, or tornadoes
bridge pins	pegs that fit into holes on the bridge of a an acoustic guitar to secure the strings.
albedo	The ratio of the outgoing solar radiation reflected by an object to the incoming solar radiation incident upon it.
video	A signal containing information on the brightness levels of different portions of an image along with information on line and frame synchronization
computer	Electronic machine capable of performing calculations and other manipulations of various types of data, under the control of a stored set of instructions
satellite revolution	The time from one perigee (the point of an elliptical orbit path where a satellite is closest to Earth) to the next.
mesoscale	The scale of meteorological phenomena that range in size from several kilometers to around 100 kilometers
hygroscopic water	Water held within 0.0002 millimeters of the surface of a soil particle
drainage basin	Land surface region drained by a length of stream channel.
pigment	Organic substance found in plant and animal cells that creates coloring.
physical geography	Field of knowledge that studies natural features and phenomena on the Earth from a spatial perspective
ocean	The salt water surrounding the great land masses
mass extinction	A catastrophic, widespread perturbation where major groups of species become extinct in a relatively short time compared to normal background extinctions.
wind chill advisory	The National Weather Service issues this product when the wind chill could be life threatening if action is not taken
ram	Random Access Memory
ground water flow	Streamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel
hertz	An international unit of frequency equal to one cycle per second, and named after a German physicist.
gymnosperm	Plant that bears naked seeds
mount rose snow sampler	A particular pattern of snow sampler having an internal diameter of 1.485 inches so that each inch of water in the sample weighs one ounce.
local visual distance	The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.
river flood	a flood on large river such as the Potomac take a tremendous amount of rain and usually develops over a period of one to two days
snow flurries	Brief occurrences of very light snow, which produce little or no accumulation.
sandstorm	A strong wind which carries sand through the air
leeward	Downwind side of an elevated area like a mountain
nasen cast	A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.
thermal low	Also known as (Heat Low), it is an area of low pressure due to the high temperatures caused by intensive heating at the surface
headward erosion	Erosion which occurs in the upstream end of the valley of a stream, causing it to lengthen its course in such a direction.
fresh water	Water found rivers, lakes, and rain, that is distinguished from salt water by its appreciable lack of salinity.
slaking	See wetting and drying.
polar air mass	An air mass that forms over a high latitude region
torsion hygrometer	A hygrometer in which the rotation of the hygrometric element is a function of humidity.
radio spectrum	The complete range of frequencies or wave lengths of electromagnetic waves, specifically those used in radio and television.
biogeochemical cycles	Movements through the Earth system of key chemical constituents essential to life, such as carbon, nitrogen, oxygen, and phosphorus.
mie scattering	Any scattering produced by spherical particles whose diameters are greater than 1/10 the wavelength of the scattered radiation
coniferous vegetation	Cone-bearing vegetation of middle and high latitudes that are mostly evergreen and that have needle-shaped or scale like leaves
hertzian waves	Radio waves or other electromagnetic radiation resulting from the oscillations of electricity in a conductor.
qpfhsd	NCEP Heavy Snow Discussion.
isotherm	Lines on a map joining points of equal temperature.
histogram	A graphical representation of a frequency distribution
condensation	The process by which water changes phase from a vapor to a liquid.
deforestation	Removal of trees from a habitat dominated by forest.
molecule	Minute particle that consists of connected atoms of one or many elements.
gene frequency	Frequency of alleles at an individual or population level.
long wave trough	A wave in the prevailing westerly flow aloft which is characterized by a large length and amplitude
thermograph	A self-recording thermometer.
calcite	Mineral formed from calcium carbonate
numerical forecasting	Forecasting the weather through digital computations carried out by supercomputers.
response time	The amount of time in which it will take a watershed to react to a given rainfall event.
driven element	See antenna.
hook echo	A radar pattern sometimes observed in the southwest (right, rear) quadrant of a tornadic thunderstorm
temperature	always expressed as a percentage.
low	A logic state corresponding to a binary "O"
thermoscreen	Same as instrument shelter.
growing season	Considered the period of the year during which the temperature of cultivated vegetation remains sufficiently high enough to allow plant growth
main lobe	The envelope of electromagnetic energy along the main axis of the radar beam.
rain	which has nearly evaporated before it reaches the ground.Dropsonde ...
sea spray	Sometimes called salt spray, it is the drops of sea water (salt water) blown from the top of a wave.
excessive heat warning	Its issued within 12 hours of the onset of the heat conditions listed in the excessive heat watch.
meteor	The former Soviet Union's series of polar-orbiting weather satellites
celestial equator	The projection of the plane of the geographical equator upon the celestial sphere.
sustained overdraft	Long-term withdrawal from the aquifer of more water than is being recharged.
mammatocumulus	An obsolete term for cumulonimbus mammatus, it is a portion of a cumulonimbus cloud that appears as a pouch or udder on the under surface of the cloud
throughflow	The roughly horizontal flow of water through soil or regolith.
stratosphere	Region of the atmosphere between the tropsphere and mesosphere, having a lower boundary of approximately 8 km at the poles to 15 km at the equator and an upper boundary of approximately 50 km
endogenic	Refers to a system that is internal to the Earth.
silicate magma	Magma that is felsic in composition.
primary wave	See P-wave.
geology	The field of knowledge that studies the origin, structure, chemical composition, and history of the Earth and other planets.
geographic isolation	See spatial isolation.
distance constant	The length of fluid flow (gas or liquid) past a sensor required for the sensor to respond to 63.2% of a step change in speed
hygrograph	A hygrometer which includes an arrangement for the time recording of atmospheric humidity.
fermentation	Decomposition and breakdown of organic matter by anaerobic means.
downwind	The direction toward which the wind is blowing; with the wind.
unconfined groundwater	Groundwater that is not restricted by impervious layers of rock.
secondary substance	Organic chemical produced by a plant that has no direct function in its metabolism
atmospheric pressure	The amount of force exerted over a surface area, caused by the weight of air molecules above it
tornado	a violently rotating column of air in contact with the ground and extending to the thunderstorm base often seen extending from near the wall cloud
esturine waters	Deepwater tidal habitats and tidal wetlands that are usually enclosed by land but have access to the ocean and are at least occasionally diluted by freshwater runoff from the land (such as bays, mouths of rivers, salt marshes, lagoons).
cut-off high	A warm high which has become displaced and is on the polarward side of the jet stream
eccentricity	Geometric shape of the Earth's orbit
wave height	Vertical distance between a wave's trough and crest.
high pressure	An area of atmospheric pressure within the Earth's atmosphere that is above average
siberian express	A fierce, cold flow of air that originates in Siberia, then moves into Alaska and northern Canada before moving southward into the United States.
hotplate precipitation gauge	An instrument which measures rainfall and snowfall by electronically maintaining the temperature of two back-to-back round plates at a constant temperature above ambient and measuring the difference of the power required to hold them at that temperature
valley	A linear depression in the landscape that slopes down to a stream, lake or the ocean
capo	a clamp that players place behind a fret across the strings to change the tone that the strings produce without re-tuning
convergence line	A horizontal line along which horizontal convergence of the airflow is occurring
heat	Heat is defined as energy in the process of being transferred from one object to another because of the temperature difference between them
detachment	One of three distinct processes involved in erosion
centripetal force	An inward-directed force that confines an object to a circular path and is equal in magnitude to the centrifugal force but in the opposite direction.
foot-lambert	A unit of luminance (photometric brightness)
solar radiation	The total electromagnetic radiation emitted by the sun
instantaneous radiative flux	An approach that involves collecting data on the distribution of radiation and the radiatively active constituents of the atmosphere and radiative properties of the lower boundary
anemometer	An instrument used for measuring the speed of the wind.
remote sensing	The technology of acquiring data and information about an object or phenomena by a device that is not in physical contact with it
runoff	The portion of the precipitation on the land which ultimately reaches the streams, especially the water from rain or melted snow that flows over the surface.
till plain	Extensive flat plain of till that forms when a sheet of ice becomes detached from the main body of the glacier and melts in place depositing the sediments it carried.
wave-cut notch	A rock recess at the foot of a sea cliff where the energy of water waves is concentrated.
instrument shelter	A boxlike structure designed to protect temperature measuring instruments from exposure to direct sunshine, precipitation, and condensation, while at the same time time providing adequate ventilation.
wyoming shield	A type of rain gauge shield consisting of two snow fences, developed by the University of Wyoming Water Resources Research Institute
instrument exposure	The physical exposure of an instrument
permian	Last geologic period in the Paleozoic era
scintillation	Generic term for rapid variations in apparent position, brightness, or color of a distant luminous object viewed through the atmosphere.
prevailing wind	A wind that blows from one direction more frequently than any other during a given period, such as a day, month, season, or year.
drizzle	Slowly falling precipitation in the form of tiny water droplets with diameters less than 0.02 inches or 0.5 millimeters
fiducial point	A point (or line) on a scale used for reference or comparison purposes
diffluence	A rate at which wind flow spreads apart along an axis oriented normal to the flow in question
steam fog	See evaporation fog.
engineering work request	Used to request engineering resources, as soon as possible, when operational, science, or engineering needs require a quick engineering response where no design or redesign is required.
rain gauge shield	A device which surrounds a rain gauge and acts to maintain horizontal flow in the vicinity of the funnel so that the catch will not be influenced by eddies generated near the gauge
cone of depression	Cone shaped depression occurring horizontally across a water table
subsidence	The slow sinking of air, usually associated with high-pressure areas.
upper mantle	Layer of the Earth's interior extending from the base of the crust to 670 kilometers below the surface
paleozoic	Geologic era that occurred from 570 to 245 million years ago.
era	Geologic time unit that is shorter than an eon but longer than a period.
mercator projection	Map projection system that presents true compass direction
rain induced fog	When warm rain falls through cooler air, water evaporates from the warm rain
physical weathering	Breakdown of rock and minerals into small sized particles through mechanical stress.
calorie	In meteorology, it is the amount of heat required to raise the temperature of one (1) gram of water one (1) degree Celsius
scree	An accumulation of weathered rock fragments at the base of a steep rock slope or cliff.
ceilometer	A device using a laser or other light source to determine the height of a cloud base
dyne	A unit of force that creates an acceleration on a mass of 1 gram equal to 1 centimeter per second
funnel cloud	A tornado that doesnt reach the ground
vapor pressure	The pressure exerted by the water vapor molecules in a given volume of air.
zone of saturation	Groundwater zone within the Earth's bedrock where all available pores spaces are filled by water
near infrared	Electromagnetic radiation with wavelengths from just longer than the visible (about 0.7 micrometers) to about two micrometers
unstable air	air that rises easily and can form clouds and rain.
bajada	Consecutive series of alluvial fans forming along the edge of a linear mountain range
glacial surge	A rapid forward movement of the snout of a glacier.
condensation	The process by which a vapor becomes a liquid
straight line winds	Generally, any wind that is not associated with rotation, used mainly to differentiate them from tornadic winds.
falsification	Falsification is a procedure used in science to test the validity of a hypothesis or theory
neutron	Atomic sub-particle found in the nucleus of an atom
charles' law	States that when the pressure is held constant, the volume of a gas varies directly with the temperature
lapse rate	The rate at which an atmospheric variable (usually temperature) decreases with elevation.
metasomatic metamorphism	Form of metamorphism that causes the chemical replacement of elements in rock minerals when gases and liquids permeate into bedrock.
eutrophic lake	Lake that has an excessive supply of nutrients, mostly in the form of nitrates and phosphates
temperature	Relative humidity A measure of how close air is to saturation at a specific temperature, always expressed as a percentage.
knot	Unit of speed of one nautical mile (6,076.1 feet) an hour.
point precipitation	Precipitation at a particular site, in contrast to the mean precipitation over an area.
surface boundary layer	The lowest layer of the earth's atmosphere, usually up to 3,300 feet, or one kilometer, from the earth's surface, where the wind is influenced by the friction of the earth's surface and the objects on it.
pulse-pair processing	Nickname for the technique of mean velocity estimation by calculation of the signal complex covariance argument
watch	A forecast issued well in advance of a severe weather event to alert the public of the possibility of a particular hazard, such as tornadoes, severe thunderstorms, flash and river floods, winter storms, or heavy snows.
advis	A program which combines the Antecedent Precipitation Index (API) method of estimating runoff with unit hydrograph theory to estimate streamflow for a headwater basin.
crosswind	A wind blowing in a direction perpendicular to the course of a moving object.
meteor	A body of matter that enters the Earth's atmosphere from space
pre-hurricane squall line	It is often the first serious indication that a hurricane is approaching
diablo winds	Dry winds in the Diablo mountain range in central California that can exceed 60 miles per hour
plate tectonics	Concept that the Earth's crust is composed of rigid plates that move over a less rigid interior.
k index	The measure of thunderstorm potential based on the vertical temperature lapse rate, the moisture content of the lower atmosphere and the vertical extent of the moist layer.
icelandic low	Subpolar low pressure system found near Iceland
calibration	Act of comparing an instrument's measuring accuracy to a known standard.
composite volcano	Volcano created from alternate layers of flows and exploded rock
national weather association	An organization whose membership promotes excellence in operational meteorology and related activities, recognizing the professional as well as the volunteer.
set	The direction towards which a current is headed
lock	See hold.
multiplexer	A device that combines several separate communications signals into one and outputs them on a single line.
ribbon falls	Spectacular narrow waterfalls that occur at the edge of a hanging valley.
constant pressure chart	A chart of a constant pressure surface in which atmospheric pressure is uniform everywhere at any given moment
wind	The movement of air relative to the surface of the earth
foliation	Process where once randomly distributed platy minerals in a rock become reoriented, because of metamorphism, in a parallel manner.
paleoclimate	Climatic conditions in the geological past reconstructed from a direct or indirect data source.
ground water mining	Pumping ground water from a basin where the safe yield is very small, thereby extracting ground water which had accumulated over a long period of time.
celestial sphere	The apparent sphere of infinite radius having the earth as its center
cold low	A low pressure system that has its coldest temperatures at or near the center of circulation, and is thermally barotropic with respect to a horizontal plane
gage zero	The elevation of zero stage
fog	A cloud on the ground.
nautical mile	The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator
silicate	Group of minerals that have crystal structures based on a silica tetrahedron (SiO4).
isohyet	Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.
richter scale	A logarithmic measurement scale of earthquake magnitude
lambert	A unit of luminance (photometric brightness)
frost wedging	A process of physical weathering in which water freezes in a crack and exerts force on the rock causing further rupture.
specific gravity	The ratio of the mass of a body to the mass of an identical volume of water at a specific temperature.
tidal zone	Area along the coastline that is influence by the rise and fall of tides.
upwelling	The process by which cold waters from the depths of a lake or ocean rise to the surface.
snow survey	Determination of the total amount of snow covering a watershed or a given region
instability	Atmospheric condition where a parcel of air is warmer that the surrounding air in the immediate environment
glacial lake	A natural impoundment of meltwater at the front of a glacier.
infiltration	The absorption and downward movement of water into the soil layer.
sublimation	The process of a solid (ice) changing directly into a gas (water vapor), or water vapor changing directly into ice, at the same temperature, without ever going through the liquid state (water)
base width	The time duration of a unit hydrograph.
sample	A sample is a subset group of data selected from a larger population group
relative evaporation	See evaporative opportunity.
depth of runoff	The total runoff from a drainage basin, divided by its area
pilot balloon	A small helium-filled meteorological balloon that is tracked as it rises through the atmosphere to determine how wind speed and direction change with altitude.
foliar leaching	Process in which water from precipitation removes plant nutrients from the surface of leaves.
high clouds	These clouds have bases between 16,500 and 45,000 feet in the mid latitudes
emanometer	An instrument for the measurement of the radon content of the atmosphere.
jet stream	A narrow band of strong winds in the atmosphere that controls the movement of high and low pressure systems and associated fronts
tropopause	The upper boundary zone or transition layer between the troposphere and the stratosphere
succulent vegetation	Group of plants that have the ability to survive in deserts and other dry climates by having no leaves
chelation	Chemical weathering process that involves the extraction or metallic cations from rocks and minerals by chelates.
anticyclone	A high-pressure system that moves in a clockwise motion
freeze-thaw action	Processes associated with daily and seasonal cycles of freezing and melting.
water cycle	The cycle of which water travels when being used over again.
smog	Originally smog meant a mixture of smoke and fog
solar eclipse	An eclipse of the sun occurs when the moon is in a direct line between the sun and the earth, casting some of the earth's surface in its shadow
nucleus	A particle of any nature upon which molecules of water or ice accumulate.
relative humidity	The ratio between the actual amount of water vapor held in the atmosphere compared to the amount required for saturation
subtropical jet stream	Relatively fast uniform winds concentrated within the upper atmosphere in a narrow band
hyphae	Thread like structures found on a fungus.
soil science	The study of soils from an interdisciplinary perspective.
aquifer	Permeable layers of underground rock, or sand that hold or transmit groundwater below the water table that will yield water to a well in sufficient quantities to produce water for beneficial use.
mean temperature	The average of temperature readings taken over a specified amount of time
millibar	A unit of atmospheric pressure equal to 1/1000 bar, or 1000 dynes per square centimeter
ecosphere	See biosphere.
divide	The topographic ridge that separates drainage basins.
cold desert	Desert found in the high latitudes and at high altitudes where precipitation is low
turbulence	An irregular motion of the atmosphere, as indicated by gusts and lulls in the wind.
seismology	A branch of science focused on the study of earthquakes and seismic activity.
adjustable emissivity	A setting on many infrared thermometers allowing you to help the thermometer calculate a more accurate temperature reading for a given material based on an estimate of its ability to emit infrared energy
polarization radar	A radar which takes advantage of ways in which the transmitted waves' polarization affect the backscattering
geohydrology	That branch of hydrology relating to subsurface, or subterranean waters.
radiation budget	A measure of all the inputs and outputs of radiative energy relative to a system, such as Earth
semi-major axis	One of the six Keplerian elements, it indicates the size of an orbit
tolerance model of succession	This model of succession suggests that the change in plant species dominance over time is caused by competition for resources
clinometer	An instrument for measuring angles of inclination
chaparral	A type of plant community common to areas of the world that have a Mediterranean climate (for example, California and Italy)
tropic of cancer	The most northern point on the earth where the sun is directly overhead on the Summer Solstice in the Northern Hemisphere, it is located at approximately 23.5 degrees North latitude.
weathering	The decay and breakup of rocks on the earth's surface by natural chemical and mechanical processes
seismic	Shaking displacement usually caused by an earthquake.
model	A mathematical representation of a process, system, or object developed to understand its behavior or to make predictions
sea level	The height or level of the sea surface at any time
tropics/tropical	The region of the earth located between the Tropic of Cancer, at 23.5 degrees North latitude, and the Tropic of Capricorn, at 23.5 degrees South latitude
convective rain	Rain associated with convective or cumuliform clouds characterized by vertical development in the form of rising mounds, domes, or towers.
vectopluviometer	A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.
hygrothermoscope	Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale
isothermal	The temperature remaining constant with height or time.
biodiversity	The diversity of different species (species diversity), genetic variability among individuals within each species (genetic diversity), and variety of ecosystems (ecosystem diversity)
discharge	Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e
canadian shield	Very old igneous and metamorphic shield rock that covers much of northern Canada
absorption	The process in which incident radiant energy is retained by a substance by conversion to some other form of energy.
seaward	Positioned or located away from land but towards an ocean or sea.
ultraviolet	Electromagnetic radiation that has a wavelength shorter than visible light and longer than x-rays
evapotranspiration	The total amount of water that is transferred from the earth's surface to the atmosphere
small circle	A circle on the globe's surface that does not bisect the center of the Earth
frets	thin metal strips (hammered into precisely spaced slots on the fingerboard) that allow players to more exactly produce specific tones.
solar noon	Point of time during the day when the Sun is aligned with True North and True South.
solstice	The point at which the sun is the furthest on the ecliptic from the celestial equator
pascal	The unit of pressure produced when one newton acts on about one square meter.
dines radiometer	An instrument for measuring radiant energy
doppler shift	The change in observed frequency of wave energy due to the relative motion of the observer and wave source
electron	A sub-particle of an atom that contains a negative atomic charge.
mammal	Group of warm blooded vertebrate animals
liquid water path	A measure of the weight of the liquid water droplets in the atmosphere above a unit surface area on the earth, given in units of kg m-2.
srh	An acronym for Storm-relative Helicity.
bcd	Binary Coded Decimal
weighing rain gauge	A precipitation gauge consisting of a receiver in the shape of a funnel which empties into a bucket mounted upon a weighing mechanism
food chain	Movement of energy through the trophic levels of organisms
attenuation	Any process in which the flux density (power) of a beam of energy is dissipated.
tropopause	The boundary zone or transition layer between the troposphere and the stratosphere
burst	A radar term for a single pulse of radio energy.
dyke	Thin vertical veins of igneous rock that form when magma enters and cools in fractures found within the crust
temperature	expressed as a percentage ...
surface based convection	Convection occurring within a surface-based layer, i.e., a layer in which the lowest portion is based at or very near the earth's surface
laser ranging	The use of lasers to measure distances.
trough	An elongated area of relatively low atmospheric pressure
visible	That part of the electromagnetic spectrum to which the human eye is sensitive, between about 0.4 and 0.7 micrometers
feed	The source of illumination for an antenna reflector
contact metamorphism	Is the small scale metamorphic alteration of rock due to localized heating
little climatic optimum	Time period from 900 - 1200 AD
crust	Earth's outer most layer of solid rock
buttress dam	Buttress dams are comprised of reinforced masonry or stonework built against concrete
leaching	Process in which water removes and transports soil humus and inorganic nutrients in solution.
crt	Cathode Ray Tube
geostationary orbit	Satellite that has an orbit that keeps it over the same point on the Earth at all times
baroclinic zone	A region in which a temperature gradient exists on a constant pressure surface
river basin	Drainage area of a river and its tributaries.
geographical coordinate system	System that uses the measures of latitude and longitude to locate points on the spherical surface of the Earth.
north pole	Surface location defined by the intersection of the polar axis with Earth's surface in the Northern Hemisphere
maximum-wind level	The height at which the maximum wind speed occurs, determined in a winds-aloft observation.
boundary layer	The atmosphere between the Earth's surface and an altitude of about 1 to 2 kilometers affected by heat and moisture.
enzyme	Are types of proteins that are used to facilitate and regulate chemical reactions within cells.
tiros	See Television and Infrared Observation Satellite.
corrective action report	Used to identify and document problems with ARM systems, physical infrastructure, or instruments.
river ice statement	A public product issued by the RFC's containing narrative and numeric information on river ice conditions.
depression storage	The volume of water contained in natural depressions in the land surface, such as puddles.
ir	See infrared.
plaentary albedo	The fraction of incident solar radiation that is reflected by a planet and returned to space
air mass	A large body of air that has nearly uniform conditions of temperature and humidity.
forminifera	Microscopic organisms of the group protozoa that are found living mainly in marine environments
miller cylindrical projection	Map projection that mathematically projects the Earth's surface onto a cylinder that is tangent at the equator
undercast	In aviation, it is an opaque cloud layer viewed from an observation point above the layer
absolute zero	The coldest possible temperature, zero on the Kelvin scale, or approximately â'273.15 Â°C, â'459.67 Â°F
rain gauge	Calibrated container that measures the amount of rainfall durinq a specific period of time.
cellulose	A type of carbohydrate
subtropical jet	Marked by a concentration of isotherms and vertical shear, this jet is the boundary between the subtropical air and the tropical air
windward	The direction from which the wind is blowing
minimum	The least value attained by a function, for example, temperature, pressure, or wind speed
stage	The level of the water surface above a given datum at a given location along a river or stream.
bankfull stage	The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index
surge	The increase in sea water height from the level that would normally occur were there no storm
mass number	Total number of neutrons and protons in the nucleus of an atom
kame	A steep conical hill composed of glaciofluvial sediments
edge wave	A wave of water that moves parallel to the shore
helicity	A property of a moving fluid, such as air, representing the potential for helical flow (flow that follows a corkscrew pattern)
parcel	A volume of air small enough to contain uniform distribution of its meteorological properties and large enough to remain relatively self-contained and respond to all meteorological processes.
producer	An organism that can synthesize the organic nutrients in requires for growth through processes like photosynthesis.
thermocouple	A temperature-sensing element which converts thermal energy directly into electrical energy
low pressure	An area of atmospheric pressure within the Earth's atmosphere that is below average
tropic of cancer	Latitude of 23.5° North
light	Visible radiation (about 0.4 to 0.7 microns in wavelength) considered in terms of its luminous efficiency, that is, evaluated in proportion to its ability to stimulate the sense of sight.
temperature	The measurement of how hot or cold something is.
detention basins	Structures which are built upstream from a populated area so that precipitation flows do not flood and cause the loss of life or property
soil colloids	Very small organic and inorganic particles found in a soil
datastream	Similar files that are in a time-sequenced series.
rain	Precipitation in the form of liquid water droplets greater than 0.5 mm
model	A simplified representation of a physical process.
submarine canyon	V-shaped canyons cut into the continental slope to a deep of up to 1200 meters
fjord	A glacial valley or glacial trough found along the coast that is now filled with a mixture of fresh water and seawater.
fracturing	Deformation process whereby ice is permanently deformed, and fracture occurs.
species diversity	Number of different species in a given region.
denitrification	Conversion of nitrates into gaseous nitrogen and nitrous oxide.
winter solstice	Astronomically, this is the date when the sun reaches it southern most point or furtherest point from the the celestial equator, theTropic of Capricorn
head wind	A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.
thunderstorm	the towering cumulus cloud has continued to grow in height and width and now lightning is occurring
rain-intensity gauge	An instrument which measures the instantaneous rate at which rain is falling on a given surface
photometer	An instrument for measuring the intensity of light or the relative intensity of a pair of lights
precambrian	Span of geologic time that dates from 4.6 billion to 570 million years ago
thematic map	Map that displays the geographical distribution of one phenomenon or the spatial associations that occur between a few phenomena
coral bleaching	Situation where coral lose their colorful symbiotic algae
sidelobe	A secondary energy maximum located outside the main radar beam
distributional limit	Spatial boundary that defines the edge of a species geographical range.
day	Considered a basic unit of time as defined by the earth's motion
flanking line	A line of cumulus clouds connected to and extending outward from the most active portion of a parent cumulonimbus, usually found on the southwest (right, rear) side of a storm
w	Degrees west longitude, referenced to the Greenwich (prime) meridian.
precambrian shield	Another term for shield.
cu	An acronym for cumulus.
rain gauge	An instrument used to measure the amount of rain that has fallen
cloud base	For a given cloud or cloud layer, the lowest level in the atmosphere at which the air contains a perceptible quantity of cloud particles.
dew	Atmospheric moisture that condenses after a warm day and appears during the night on cool surfaces as small drops
stormwater discharge	Precipitation that does not infiltrate into the ground or evaporate due to impervious land surfaces, but instead flows onto adjacent land or water areas and is routed into drain/sewer systems.
flood plain	Level land that may be submerged by flood waters.
true freezing point	The temperature at which the liquid and solid forms of a substance may exist in equilibrium at a given pressure (usually one standard atmosphere)
relocated	A term used in an advisory to indicate that a vector drawn from the preceding advisory position to the latest know position is not necessarily a reasonable representation of the cyclone's movement.
freezing rain	rain that falls onto a surface with a temperature below freezing causing it to freeze to the surface forming a coating of ice or glaze.
freeze	It occurs when the temperature falls below 32 degrees over a large area for an extended period of time.
evaporation	To change water or liquid into vapor.
transmissivity	A measure of luminous flux remaining in a light beam after it has passed through a specified distance of the atmosphere.
isobaric	Of equal or constant pressure, with respect to either space or time.
local winds	Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.
float barograph	A type of recording siphon barometer
passive remote sensing	Form of remote sensing where the sensor passively captures electromagnetic radiation reflected or emitted by an object.
stability	The capability of a system to tolerate or recover from disturbance or an environmental stress.
glacial uplift	Upward movement of the Earth's crust following isostatic depression from the weight of the continental glaciers.
elevation	The measure of height with respect to a point on the earth's surface above mean sea level
rain gage	A device, usually a cylindrical container, for measuring rainfall.
oxbow lake	Is portion of abandoned stream channel filled with stagnant water and cut off from the rest of the stream
clone	A person or thing very much like another, e.g., a copy of another manufacturer's computer.
photon	A quantum (smalles unit in which waves may be emitted or absorbed) of light.
passive system	A system sensing only radiation emitted by the object being viewed or reflected by the object from a source other than the system
delta	Large deposit of alluvial sediment located at the mouth of a stream where it enters a body of standing water.
wave crest	The highest point in a wave.
figure	a distinctive pattern in wood created by its grain, annual rings, medullary and color variation
bedrock	Rock at or near (beneath soil and regolith) the Earth's surface that is solid and relatively unweathered.
pascal's law	A hydrostatic principle that pressure supplied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the containing vessel.
sand sea	A large region of sand and sand dunes in a desert
doldrums	Area of low atmospheric pressure and calm westerly winds located at the equator
surface	Precipitation featuring tiny water droplets 200-500 microns in diameter
snow advisory	A statement or advisory issued when snow is expected to create hazardous travel conditions
hz	See Hertz.
shield	A large stable area of exposed very old (more than 600 million years) igneous and metamorphic rock found on continents
interception	Is the capture of precipitation by the plant canopy and its subsequent return to the atmosphere through evaporation or sublimation
water vapor	Its a gas in the atmosphere
uv	Ultraviolet
thermodynamics	Study of the processes that involve the transformation of heat into mechanical work, of mechanical work into heat, or the flow of heat from a hotter body to a colder body.
esturine zone	The area near the coastline that consists of estuaries and coastal saltwater wetlands.
lotic system	A flowing body of fresh water, such as a river or stream
divergence	A measure of the expansion or spreading out of a vector field; usually said of horizontal winds
storm tracks	The path or tracks generally followed by a cyclonic disturbance.
flood tide	Time during the tidal period when the tide is rising
aerosol particle size	Linear size (e.g
rainwash	The erosion of soil by overland flow
plasma	A fourth state of matter (in addition to solid, liquid, and gas) that exists in space
environment	The external conditions and surroundings, especially those that affect the quality of life of plants, animals and human beings.
phylum	A group or category used in the taxonomic and/or phylogenic classification of organisms
sinkhole	A pit like hole in found in areas of karst
particle number concentration	The number of particles present in any given volume of air.
evaporative power	A measure of the degree to which the weather or climate of a region is favorable to the process of evaporation
evaporite	Type of sedimentary rock that is formed from the concentration of dissolved salts through evaporation.
channel routing	The process of determining progressively timing and shape of the flood wave at successive points along a river.
magma	Molten rock originating from the Earth's interior.
wire weight gauge	A river gauge in which a weight suspended on a wire is lowered to the water surface from a bridge or other overhead structure to measure the distance from a point of known elevation to the water surface.
reduction	In general, the transformation of data from a "raw" form to some useable form
drift	The variation over a period of time in device output when the input parameter is fixed
clay	Mineral particle with a size less than 0.004 millimeters in diameter
isobaric chart	Same as a constant pressure chart.
ice sheet	A dome-shaped glacier covering an area greater than 50,000 square kilometers
precession of the equinox	Wobble in the Earth's polar axis
channel storage	The water volume within a specified portion of a stream channel.
gerdien aspirator	An instrument used for the determination of the electrical conductivity of the atmosphere.
plan position indicator	Also known as a PPI Scope, it is a radar indicator scope displaying range and azimuth of targets in polar coordinates.
wave trough	The lowest point in a wave.
mmts	Maximum-Minimum Temperature System
muggy	A subjective term for warm and excessively humid weather.
ground water overdraft	Pumpage of ground water in excess of safe yield.
rain gauge	Instrument for measuring the depth of water from precipitation that is assumed to be distributed over a horizontal, impervious surface and not subject to evaporation.
equinox	The point at which the ecliptic intersects the celestial equator
black ice	Thin, new ice on fresh or salt water that appears dark in color because of its transparency
pluviometer	Same as rain gauge.
ip rating	A measure of an instrument's protection against the ingress of dust, water and other substances into the equipment
snow accumulation	The actual depth of snow on the ground at any instant
fire danger	The result of both constant factors (fuels) and variable factors (primarily weather), which affects the ignition, spread, and difficulty of control of fires and the damage they cause.
frost	the formation of ice crystals in the forms of scales, needles, feathers, or fans, which develop under conditions similar to dew, except that the temperature has dropped to at least 32�F.
inversely proportional	Cause and effect relationship between two variables where a positive or negative change in the quantity of one causes a predictable opposite change in quantity in the other.
backscattering	Portion of solar radiation directed back into space as a result of particle scattering in the atmosphere.
winter	Season between fall and spring
earth	The third planet from the sun and is our home.
reproducibility	The closeness of agreement among measurements of the same value of the same quantity where the individual measurements are made under different defined conditions, i.e
meridional	Movement of wind or ocean waters in a direction that is roughly perpendicular to the lines of latitude.
sandstorm	A strong wind carrying sand particles through the air
glaze	Coating of ice that forms when rain falls on a surface with a temperature below freezing.
river recreation statement	A statement released by the NWS to inform river users of current and forecast river and lake conditions
corner effects	A small-scale convergence effect that can be quite severe
parachute radiosonde	Same as dropsonde.
pluvial	In hydrology, anything that is brought about directly by precipitation.
legume	Angiosperm plant species that is a member of the Fabaceae (Pea or Bean) family
cartography	Field of knowledge that studies map construction
oxisol	Soil order (type) of the United States Natural Resources Conservation Service Soil Classification System
precipitation scavenging	Removal of pollutants from the air by either rain or snow.
probability	Statistical chance that an event will occur.
breaker	The quick collapse of an overextended water wave as it approaches the shoreline
seed dispersal	Movement of a plant seed away from the parent plant by a passive or active mechanism.
azimuth angle	1
movable bed	A stream bed made up of materials readily transportable by the stream flow.
longitude	The location east or west in reference to the Prime Meridian, which is designated as zero (0) degrees longitude
albedo	The ratio of the amount of radiation reflected from an object's surface compared to the amount that strikes it
terminal velocity	Maximum speed that can be achieve by a body falling through a fluid like water or air.
eta model	One of the operational numerical forecast models run at NCEP
beaufort wind scale	Descriptive system that determines wind speed by noting the effect of the wind on the environment
mixing ratio	The ratio between the weight (mass) of water vapor (or some other gas) held in the atmosphere compared to the weight of the dry air in a given volume of air
spectral band	A finite segment of wavelengths in the electromagnetic spectrum.
meteorology	The study of the atmosphere and atmospheric phenomena as well as the atmosphere's interaction with the earth's surface, oceans, and life in general
ocean trench	Deep depression found at the edge of the ocean floor
depression	In meteorology, an area of low pressure; a low or trough.
free lift	The actual lifting force of an inflated balloon, usually expressed in grams.
uars	See Upper Atmosphere Research Satellite.
haploid	Cell that contains only one set of chromosomes
vip	Video Integrator and Processor, which contours radar reflectivity (in dBZ) into six VIP levels:
net primary productivity	Total amount of chemical energy fixed by the processes of photosynthesis minus the chemical energy lost through respiration.
r horizon	Soil horizon found beneath the C horizon
pathogen	Microscopic parasite organism that causes disease in a host
ephemeris	A tabulation of a series of points that define the position and motion of a satellite
infiltration capacity	The maximum rate at which precipitation can pass through the surface into the soil, for a given soil in a given condition.
saturation point	The point when the water vapor in the atmosphere is at its maximum level for the existing temperature.
ifov	Instantaneous Field of View
dead band	The range through which the input may be varied without initiating a response
coriolis force	The apparent tendency of a freely moving particle to swing to one side when its motion is referred to a set of axes that is itself rotating in space, such as Earth
tracking	The lowest value of a measured quality at which a sensor meets its accuracy specification.
low level wind shear	A local variation in the wind direction or speed
pedology	The scientific study of soils.
reconnaissance code	An aircraft weather reconnaissance code that has come to refer primarily to in-flight tropical weather observations, but actually signifies any detailed weather observation or investigation from an aircraft in flight.
dust devil	Small whirlwinds of dust that form in dry areas like deserts
immigration	Migration of an organism into an area for the purpose of changing its residence permanently
soil erosion	Transport of soil mineral particles and organic matter by wind, flowing water, or both
salinization	Pedogenic process that concentrates salts at or near the soil surface because evapotranspiration greatly exceeds water inputs from precipitation.
antarctic ocean	Although not officially recognized as a separate ocean body, it is commonly applied to those portions of the Atlantic, Pacific, and Indian Oceans that reach the Antarctic continent on their southern extremes.
gamma radiation	A type of ionizing, electromagnetic radiation that readily penetrates the body tissues of organisms
crater	Circular depression in the ground surface created by volcanic activity or asteroid impact.
bear's cage	Slang for a region of storm-scale rotation, in a thunderstorm, which is wrapped in heavy precipitation
diurnal tide	Tides that have one high and one low water per tidal period.
upper air/upper level	The portion of the atmosphere which is above the lower troposphere
persistence	The length of time during which a signal is visible on a radar display.
volcanic vent	An opening on a volcano through which lava is released and rock fragments and ash are ejected.
organelle	Is a specialized structure found in cells that carry out distinct cellular functions.
southeast trade winds	See trade winds.
facilitation	Modification of a system that makes subsequent modifications easier.
rass	Abbreviation for radio acoustic sounding system.
temperature	A measure of the warmth of the ambient air measured by a suitable instrument such as a thermometer.
trough	An elongated area of low atmospheric pressure that is associated with an area of minimum cyclonic circulation
litterfall	Movement of leaves, twigs and other forms of organic matter from the biosphere to the litter layer found in soil.
sea surface temperature	The temperature of the water's surface
polar-orbiting satellite	A satellite whose orbit passes over both of the earth's between poles.
polarimeter	An instrument for determining the degree of polarization of light
tweb	Acronym for Transcribed WEather Broadcast.
tombolo	A coastal feature that forms when a belt sand and/or gravel is deposited between an island and the mainland
reference map	Map that shows natural and human-made objects from the geographical environment with an emphasis on location
tropical disturbance	An area of organized convection, originating in the tropics and occasionally the subtropics, that maintains its identity for a least 24 hours or more
tropical disturbance	An organized group of thunderstorms often found over a tropical ocean that generates a slight cyclonic flow of less than 37 kilometers per hour
backplane	Area of a computer or other device where various logic and control elements are interconnected
sawrs	Supplemental Aviation Weather Reporting Station
wasatch winds	Strong winds blowing easterly out of the Wasatch Mountains in Utah, sometimes reaching speeds greater than 75 miles per hour.
erosion	The wearing away of the Earths surface by the action of the sea, running water, moving ice, precipitation or wind.
ice cap	Large dome-shaped glacier found covering a large expanse of land
statute mile	A unit of distance equal to 5280 feet
partial-duration flood series	A list of all flood peaks that exceed a chosen base stage or discharge, regardless of the number of peaks occurring in a year.
standard surface pressure	The measurement of one atmosphere of pressure under standard conditions
indefinite quantity	an estimated quantity
electromagnetic energy	Energy stored in electromagnetic waves or radiation
mesonet	A regional network of observing stations (usually surface stations) designed to diagnose mesoscale weather features and their associated processes.
opisometer	Mechanical device for measuring non-linear distances on maps.
freezing rain	A type of precipitation
divide	The high ground that forms the boundary of a watershed
orthographic projection	Map projection that presents the Earth's surface in two-dimensions as if it were being observed from a great distance in space
range	A statistical measure of the dispersion of observation values in a data set
biomass	The amount of living material in unit area or volume, usually expressed as mass or weight.
flood crest	The Maximum height of a flood wave as it passes a location.
stationary front	A front which is nearly stationary or moves very little since the last synoptic position
candle	A unit of luminous intensity of a light source
gas thermometer	A thermometer which utilizes the thermal properties of gas
rod	A graduated staff used in determining the difference in elevation between two points
tropospheric emission spectrometer	A high-resolution infrared spectrometer for monitoring the minor components of the lower atmosphere.
gradient	The steepness of a slope as measured in degrees, percentage, or as a distance ratio (rise/run).
limestone	Sedimentary rock composed of carbonate minerals, especially calcium carbonate
earthquake	The shaking or movement of a portion of the Earth's surface.
vertical visibility	The distance an observer can see vertically into an undefined ceiling, or the height corresponding to the top of a ceiling light projector beam, or the height at which a ceiling balloon disappears during the presence of an indefinite ceiling.
organic soil	Soil order (type) of the Canadian System of Soil Classification
isotherm	A line of equal or constant temperature.
technical support branch	One of three branches of the Tropical Prediction Center (TPC)
foreset bed	Deltaic deposit of alluvial sediment that is angled 5 to 25° from horizontal
condensation nucleus	Small particle on which water vapor condenses.
parity	The addition of one or more redundant bits to information to verify its accuracy.
needle ice	A form of periglacial ground ice that consists of groups ice slivers at or immediately below the ground surface
pressure change	The net difference between pressure readings at the beginning and ending of a specified interval of time.
evergreen vegetation	Vegetation that keeps a majority of their leaves or needles throughout the year
constantan	A copper-nickel alloy used as the negative lead in Type E, Type J, and Type T thermocouples.
cliff	A tall steep rock face.
pitot tube	A device for measuring the velocity of flowing water using the velocity head of the stream as an index of velocity
summation layer amount	The amount of sky cover for each layer is given in eighths of sky cover attributable to clouds or obscurations
sinusoidal equal-area projection	Map projection that represents areas in their true form on a two-dimensional map
luvisol soil	Soil order (type) of the Canadian System of Soil Classification
quadrant electrometer	A very sensitive electrostatic electrometer for measuring small potential differences.
classification	Process of grouping things into categories.
ground frost	Frost that penetrates the soil surface in response to freezing temperatures.
atmospheric pressure	The pressure exerted by the earth's atmosphere at any given point, determined by taking the product of the gravitational acceleration at the point and the mass of the unit area column of air above the point.
radiant energy	The energy of any type of electromagnetic radiation
blowing snow	Wind-driven snow that causes reduced visibility and sometimes significant drifting
ultraviolet radiation	An electromagnetic radiation with wave-lengths longer than X-rays but shorter than visible light.
proportional	Cause and effect relationship between two variables where a positive or negative change in the quantity of one causes a predictable similar quantity change in the other.
wind shear	The rate of change of wind speed and/or direction over a given distance
barometric pressure	Same as atmospheric pressure.
software	The programs, data, or routines used by a computer, distinguished from the physical components (e.g., hardware).
coalescence	Process where two or more falling raindrops join together into a single larger drop because of a midair collision.
sensor	The part of a measuring instrument which responds directly to changes in the environment.
transparency	The ability of a medium to allow light to pass through it.
foot-candle	A unit of illuminance or illumination equal to one lumen per square foot
air stagnation	A meteorological situation in which there is a major buildup of air pollution in the atmosphere
earthen dam	An embankment dam in which more than 50% of the total volume is formed of compacted fine-grained material
fahrenheit	A scale of temperature originally defined by having 0Â° as the lowest obtainable temperature with a mixture of water, ice and salt and 96Â° as the temperature of the human body
sine galvanometer	A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.
transponder ranging	An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.
dew	Water that forms on objects close to the ground when its temperature falls below the dew point of the surface air.
nitrogen oxides	Consists of two gases nitric oxide (NO) and nitrogen dioxide (NO2)
estuary	Somewhat enclosed coastal area at the mouth of a river where nutrient rich fresh water meets with salty ocean water.
rainsplash	Soil erosion caused from the impact of raindrops.
spot image	Company that markets data gathered by the SPOT satellite worldwide.
reflection	The return of light or sound waves from a surface
fall	a free and rapid descent by the force of gravity
period	Geologic time unit that is shorter than an era but longer than a epoch.
hydrosphere	Considered as the water portion of the earth's surface
cell	A cell is the smallest self-functioning unit found in living organisms
snow cover	The areal extent of ground covered by the snow
compensation	An addition of specific materials or devices to counteract a known error.
solid-state device	An element that can control current without moving parts, heated filaments, or vacuum gaps.
isohel	A line drawn through geographic points having equal duration of sunshine or another form of solar radiation during a specified time period.
circulation	The flow or motion of a fluid in or through a given area or volume
perihelion	The point in the orbit of a planet or comet which is nearest the Sun (as opposed to the aphelion, which is the point in the orbit farthest from the Sun).
gravity	Is the process where any body of mass found in the universe attracts other bodies with a force proportional to the product of their masses and inversely proportional to the distance that separates them
infiltration index	An average rate of infiltration, in inches per hour, equal to the average rate of rainfall such as that the volume of rainfall at greater rates equals the total direct runoff.
urban flooding	Flooding of streets, underpasses, low lying areas, or storm drains
sublimation	The process whereby ice changes directly into water vapor without melting
accuracy	Degree of conformity of a measure to a standard or true value.
black blizzard	A local term for a violent duststorm on the south-central Great Plains that darkens the sky and casts a pall over the land.
solstice	Dates when the declination of the Sun is at 23.5° North or South of the equator
nitrogen cycle	Model that describes the movement of nitrogen in its many forms between the hydrosphere, lithosphere, atmosphere and biosphere.
thermal high	Area of high pressure in the atmosphere caused by the area having warmer temperatures relative to the air around it.
weather	It describes the condition of the air at a particular time and place
urban area	Geographic area with a high density of people over a limited area
mercury thermometer	A liquid-in-glass or liquid-in-metal thermometer using mercury as the liquid.
threshold velocity	Velocity required to cause entrainment in the erosional agents of wind, water or ice
dust devil	A small, rapidly rotating column of wind, made visible by the dust, dirt or debris it picks up
synoptic chart	Any map or chart that depicts meteorological or atmospheric conditions over a large area at any given time.
humus	Dark colored semi-soluble organic substance formed from decomposition of soil organic matter.
hydration	A form of chemical weathering that involves the rigid attachment of H+ and OH- ions to the atoms and molecules of a mineral.
optical depth	A measure of how much light airborne particles, whether aersols, cloud droplets, or ice particles, prevent from passing through a column of atmosphere.
creeping	Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.
range unfolding	Process of removing range ambiguity in apparent range of a multitrip target on the radar.
oceanic plate	A rigid, independent segment of the lithosphere composed of mainly basalt that floats on the viscous plastic asthenosphere and moves over the surface of the Earth
bearing	A system that measures in reference to the cardinal points of a compass in 90 degree quadrants.
trough	On a weather chart, a narrow, elongated area of relatively low pressure.
rill	A very small steep sided channel carrying water
thermometer screen	Same as instrument shelter.
type j	A specialized thermocouple sensor pairing two wires made mostly of iron and constantan and using variance in voltage to calculate temperaturesâmore limited in its range to higher temperatures but known for its sensitivity.
typhoon	Another name for hurricane.
biome	Well-defined terrestrial environment (e.g., desert, tundra, or tropical forest)
syzygy	The instance (new moon or full moon) when the earth, sun, and moon are all in a straight line.
sleet warning	Its issued when accumulations of sleet in excess of a half inch are expected
isohyet	The line drawn through geographic points recording equal amounts of rainfall during a given time or for a given of storm.
tertiary	Geologic period that occurred roughly 1.6 to 65 million years ago
revolution	See Earth revolution.
el niño	The unusual warming of the surface waters of the eastern tropical Pacific Ocean
density current	A flow of water maintained by gravity through a large body of water, such as a reservoir or lake, and retaining its unmixed identity because of a difference in density.
current	A horizontal movement of water, such as the Gulf Stream off the east coast of North America, or air, such as the jet stream.
carbon dioxide concentration	The amount of carbon dioxide, a heavy, colorless greenhouse gas, per unit of volume.
dia.	Diameter
trade winds	Winds which blow from tropical high pressure belts toward the equatorial region of low pressure
sampling	The process of obtaining a sequence of discrete digital values from a continuous sequence of analog data.
thermodynamic temperature	A measure, in kelvins (K), proportional to the thermal energy of a given body at equilibrium
constant-level balloon	A balloon designed to float at a constant pressure level
short wave	A progressive wave of smaller amplitude, wave length, and duration than a long wave
condensation	The change in state of matter from vapor to liquid that occurs with cooling
lightning discharge	The series of electrical processes by which charge is transferred along a channel of high ion density between electrical charge centers of opposite sign
virga	Precipitation falling from a cloud, usually in wisps or streaks, but evaporating before it reaches the ground.
temperature	the greater the number of water molecules the air can hold
perched water table	The water table of a relatively small ground-water body supported above the general ground water body.
antenna array	An ordered assembly of elementary antennae spaced apart and fed in such a manner that the resulting radiation is concentrated in one or more directions.
rip current	A strong relatively narrow current of water that flows seaward against breaking waves.
scattering	The process by which electromagnetic radiation interacts with and is redirected by the molecules of the atmosphere, ocean, or land surface
fathom	A unit of length equal to six feet which is used to measure the depth of water.
compass points	The cardinal points of the compass, i.e
closed basin	A basin draining to some depression or pond within its area, from which water is lost only by evaporation or percolation
front	The transition zone or interface between two air masses of different densities, which usually means different temperatures
secchi disk	A white disk 12" or more in diameter which is lowered into the sea to estimate transparency of the water
watercourse	Any surface flow such as a river, stream, tributary.
rain gauge	An instrument for measuring rainfall.
eukaryote	Organisms whose cells have a membrane-bound nucleus and many specialized structures located within their cell boundary
few	The amount of sky cover for a cloud layer between 1/8th and 2/8ths, based on the summation layer amount for that layer.
telemeter	The measuring, transmitting, receiving, and indicating apparatus for obtaining the value of a quantity at a distance.
water balance	Balance of the water resources of a region, comparing precipitation and inflow with outflow, evaporation, and accumulation.
station pressure	The pressure that is read from a barometer but is not adjusted to sea level.
freeze	It is when the surface air temperature is expected to be 32°F or below over a widespread area for a climatologically significant period of time
photoelectric photometer	See photometer.
parhelion	Either of two colored luminous spots that appear at points 22° (or somewhat more) on both sides of the sun and at the same elevation as the sun
windward	Situated on the side from which the wind blows.
flood	Overflowing by water of the normal confines of a stream or other body of water, or accumulation of water by drainage over areas which are not normally submerged.
evaporation opportunity	The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power
thermometer	An instrument used for measuring temperature
bourdon tube	Closed, curved, flexible tube of elliptic cross section which is deformed, according to type, by variations of atmospheric pressure or temperature and so provides a measurement of the particular parameter.
ecology	The study of the factors that influence the distribution and abundance of species.
soil moisture recharge	The process of water filling the pore space found in a soil (storage).
fissure	Opening or crack in the Earth's crust.
overrunning	A weather pattern in which a relatively warm air mass is in motion above another air mass of greater density at the surface
acquisition of signal	The time you begin receiving a signal from a spacecraft
pressure altimeter	An aneroid barometer with a scale graduated in altitude instead of pressure units.
downdraft	Downward-moving air, usually within a thunderstorm cell.
raws	Remote Automated Weather Station
spheroidal weathering	A type of below ground chemical weathering where the corners of jointed rocks become rounded over time
gross primary productivity	Total amount of chemical energy fixed by the processes of photosynthesis.
cap	Composed of a layer of warmer, dryer air aloft which may suppress or delay the development of thunderstorms
flood stage	The level of a river or stream where overflow onto surrounding areas can occur.
positive feedback	Change in the state of a system that enhances the measured effect of the initial alteration.
meteorology	Study of the atmosphere and its phenomena.
lizard balloon	A balloon having a detachable tail which is released when the balloon has undergone a predetermined expansion
deflation	Process where wind erosion creates blowout depressions or deflation hollows by removing and transporting sediment and soil.
aerosol absorption	The process in which radiation energy is retained by aerosols.
fluid	Substance, gas or liquid, that has the property of flow.
hail	Snow - Precipitation composed of white or translucent ice crystals
caldera volcano	Explosive type of volcano that leaves a large circular depression
barometer	An instrument that measures atmospheric pressure
transform fault	Massive strike-slip fault continental in size
broken	An official sky cover classification for aviation weather observations, descriptive of a sky cover of 5/8 to 7/8
self-regulation	The ability of some systems to maintain a steady state equilibrium through positive and negative feedbacks.
ozone	A nearly colorless gas and a form of oxygen (O2)
uncertainty	An expression of the possible measurement error for a given instrument over a specified range
insolation	Incoming solar radiation
raindrop impact	Force exerted by a falling raindrop on a rock, sediment, or soil surface.
total column ozone	A measurement of ozone concentration in the atmosphere.
ozone	A form of oxygen that has a weak chlorine odor
ultisols	Soil order (type) of the United States Natural Resources Conservation Service Soil Classification System
intermittent stream	A stream that flows only for short periods over a year
mississippian	Geologic period that occurred roughly 320 to 360 million years ago
rotation	See Earth rotation.
pressure	Is defined as the force acting on a surface from another mass per unit area.
rift	Zone between two diverging tectonic plates
circadian rhythm	The cyclical changes in physiological processes and functions that are related to the 24-hour diurnal cycle.
bankfull stage/elevation	An established river stage/water surface elevation at a given location along a river which is intended to represent the maximum water level that will not overflow the river banks or cause any significant damages from flooding.
diurnal	Pertaining to actions or events that occur during a twenty-four hour cycle or recurs every twenty-four hours
threshold	The lowest value of a measured quality at which a sensor responds
glacier dammed lake	The lake formed when a glacier flows across the mouth of an adjoining valley and forms an ice dam.
lake effect snow	Snow showers that are created when cold dry air passes over a large warmer lake, such as one of the Great Lakes, and picks up moisture and heat.
peak wind speed	The maximum instantaneous wind speed since the last observation that exceeded 25 knots.
critical flow	A condition of flow where the mean velocity is at one of the critical values; ordinarily at Belanger's critical depth and velocity
protoplasm	Substances making up a cell including its exterior membrane.
law of stream number	Morphometric relationship observed in the number of stream segments of a particular classification order in stream channel branching
aquiclude	A formation which contains water but cannot transmit it rapidly enough to furnish a significant supply to a well or spring.
competitive exclusion	Situation where no two competitively interacting species can occupy exactly the same fundamental niche indefinitely because of resource limitations
resource partitioning	The evolutionary process of species living in the same ecosystem dividing up resources so that each species develops dissimilar resource requirements to avoid competition
dense fog advisory	Advisory issued when fog reduces visibility to 1/8 mile or less, creating possible hazardous conditions.
evaporation	Change from a liquid (more dense) to a vapor or gas (less dense) form
flash flood	a flood that occurs suddenly during or shortly following heavy rains or from a sudden release of water as in a dam break
glacial milk	Term used to describe glacial meltwater which has a light colored or cloudy appearance because of clay-sized sediment held in suspension.
trade winds	Are two belts of prevailing winds that blow easterly from the subtropical high pressure centers towards the equatorial trough
sulfate aerosol	Type of solid compound commonly found in the atmosphere
earth sciences tradition	Academic tradition in modern Geography that investigates natural phenomena from a spatial perspective.
triple-point temperature	The temperature at which all three phases of a substance can exist in equilibrium
hydraulic permeability	The flow of water through a unit cross-sectional area of soil normal to the direction of flow when the hydraulic gradient is unity.
flurries	Light snowfall that generally does not produce a measurable accumulation.
fossil	Hardened remains or traces of plant or animal life from a previous geological period preserved in the Earth's crust.
kelvin-helmoltz waves	Vertical waves in the air associated with wind shear across statically stable regions
thunderstorm	A storm produced by a cumulonimbus cloud and always has lightning and thunder
hrpt	See High Resolution Picture Transmission.
zenith	The point which is elevated 90 degrees from all points on a given observer's astronomical horizon
lidar	Light Detecting And Ranging
catastrophism	General theory that suggests that certain phenomena on the Earth are the result of catastrophic events
hurricane	An intense cyclonic storm consisting of an organized mass of thunderstorms that develops over the warm oceans of the tropics
heating degree day	One heating degree day is given for each degree that the daily mean temperature is below 65°F
percolation	The gravity flow of water within soil.
black carbon concentration	The concentration of carbon in its very absorbing, elemental, non-organic, non-oxide form (e.g
sea ice	Ice that is formed by the freezing of sea water
volmet broadcast	Routine broadcast of meteorological information for aircraft in flight.
harmonics	bell-like tones that ring at frequencies that are multiples of the frequency of the fundamental note
centibar	The pressure unit of the meter-ton-second system of physical units, equal to 10 millibars or 104 dynes per cm².
col	Saddle like depression found between two mountain peaks
isotopic dating	Dating technique used to determine the age of rock and mineral through the decay of radioactive elements.
palsa	A mound of peat that develops as the result of the formation of a number ice lenses beneath the ground surface
near-surface soil moisture flux	A quantity measured near the surface of the soil, according to the formula B = λ(dq/dz), where λ is the conductivity of the soil that the heat or moisture is moving through.
automatic picture ttansmission	System developed to make real-time reception of satellite images possible whenever an APT- equipped satellite passes within range of an environmental satellite ground station
transpiration	Transpiration is the process of water loss from plants through stomata
condensation	The change of water vapor to liquid water, as when fog or dew forms.
dbz	A logarithmic expression for reflectivity factor, referenced to (1 mm6 / 1 m3)
nutrient cycle	The cycling of a single element by various abiotic and biotic processes through the various stores found in the biosphere, lithosphere, hydrosphere, and atmosphere.
estimator	An estimator is any value calculated from the sample data For example, the sample mean is an estimator of the population mean.
tide	Cyclical rise and fall of the surface of the oceans
coriolis force	An apparent force due to the Earth's rotation
daily mean	The average temperature for a day computed by averaging either the hourly readings or, more commonly, the maximum and minimum temperatures.
afforestation	The act or process of establishing a forest, especially on land not previously forested.
water year	Any twelve-month period, usually selected to begin and end during a relative dry season
normal lapse rate	Average rate of air temperature change with altitude in the troposphere
candlepower	Luminous intensity expressed in candelas.
pc	Personal computer.
bowen reaction series	Model that explains the origin of the various types of igneous rocks
brown snow	Snow intermixed with dust particles
rdf	Radio Direction Finder.
pitted topography	Landscape characterized by numerous kettle holes on a glacial outwash plain.
shortwave radiation	Electromagnetic radiation with a wavelength between 0.1 and 0.7 micrometers (µm)
degree hour	As used by the U.S
wake	The region of turbulence immediately to the rear of a solid body caused by the flow of air over or around the body.
absorption	The process in which radiant energy is retained by a substance
map scale	Ratio between the distance between two points found on a map compared to the actual distance between these points in the real world.
direct solar radiation	Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source
conduction	Conduction consists of energy transfer directly from atom to atom and represents the flow of energy along a temperature gradient.
nimbostratus	A dark, gray cloud characterized by more or less continuously falling precipitation
condensation funnel	A funnel-shaped cloud associated with rotation and consisting of condensed water droplets (as opposed to smoke, dust, debris, etc.)
ppm	See parts per million.
sea breeze	Local coastal wind that blows from the ocean to land
sky brightness temperature	A descriptive measure of radiation in terms of the temperature of a hypothetical black body emitting an identical amount of radiation at the same wavelength.
yellow snow	Snow given a golden or yellow appearance by the presence in it of pine, cypress pollen, or anthropogenic material or animal-produced material
legend	A listing that contains symbols and other information about a map.
free ground water	Unconfined ground water whose upper boundary is a free water table.
frigophobia	The fear of the cold and cold things.
surface stress	The vertical flux of momentum near the surface as the the ambient flow interacts with the land/water surface.
heat capacity	Is the ratio of the amount of heat energy absorbed by a substance compared to its corresponding temperature rise.
overcast	when more than 9/10ths of the sky is covered with clouds
bow echo	A radar echo signature often associated with severe thunderstorms, especially those that produce wind damage
index contour	Contour line that is accentuated in thickness and is often labeled with the appropriate measure of elevation
pedon	A basic soil sampling unit
detritivore	Heterotrophic organism that feeds on detritus
stability	The degree of resistance of a layer of air to vertical motion.
digital	Pertaining to measurements or devices in which the output varies in discrete steps, i.e
hypothermia	when the body temperature drops below 95�F.
pressure tendency	The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).
fold	Wavelike layers in rock strata that are the result of compression.
synoptic chart	Chart showing meteorological conditions over a region at a given time; weather map.
hardware	Physical equipment used in data processing
light year	Distance that light travels in the vacuum of space in one year
flash flood	A flood which follows within a few hours (usually less than 6 hours) of heavy or excessive rainfall, dam or levee failure, or the sudden release of water impounded by an ice jam
discontinuity	Comparatively large contrast in meteorological elements over a relatively small distance or period of time
convection	Motions in a fluid that transport and mix the properties of the fluid
input	Addition of matter, energy, or information to a system
evaporation	The process by which a liquid changes into a gas.
reservoir volume	The volume of a reservoir when filled to normal pool or water level.
direct runoff	The runoff entering stream channels promptly after rainfall or snowmelt
hydrogen	A colorless and odorless gaseous element
conduction	The trasnfer of electrical energy or heat through or by means of a conductor.
filling	An increase in the central pressure of a pressure system; opposite of a deepening
mass wasting	General term that describes the downslope movement of sediment, soil, and rock material.
coalescence	Formation of a single water drop by the union of two or more colliding drops.
groundwater recharge	The replenishment of groundwater with surface water.
magnetic poles	Either of the two points on the earth's surface where the magnetic meridians converge
detention storage	The volume of water, other than depression storage, existing on the land surface as flowing water which has not yet reached the channel.
slant range	The line-of-sight distance between two objects.
rating curve	A graph showing the relationship between the stage, usually plotted vertically (Y-axis) and the discharge, usually plotted horizontally (X-axis).
near-real time	When referred to in textual references, the ARM conception of "near-real time" is "with a few hours delay."
permafrost	See cryosphere.
ips	Inches per second.
auto-off	The ability of a device to turn itself off to conserve power after a specified period of time without any user inputs
stoss	Side of a slope that faces the direction of flow of ice, wind, or water
ice	The solid form of water
antenna	A wire or set of wires used to send and receive electromagnetic waves
muskingum method	A method of streamflow routing which assumes that storage is a linear function of the weighted flow in the reach and is adaptable to a simple mathematical solution.
precipitation-effectiveness ratio	Same as precipitation-evaporation ratio.
rain shadow	Also referred to as a precipitation shadow, it is the region on the lee side of a mountain or similar barrier where the precipitation is less than on the windward side
fair	This is a subjective description
cirrus	Wispy-looking cloud belonging to a class characterized by thin white filaments or narrow bands and a composition of ice crystals
ph	A measure of the acidity or alkalinity of a substance, using numerical values from 0 (maximum acidity) through 7 (neutral) to 14 (maximum alkalinity).
firn	Old snow that has become granular and compacted as a result of melting and refreezing.
irradiance	The rate at which radiant energy in a radiation field is transferred across an area of a surface (real or imaginary) in a hemisphere of directions.
cardinal points	The four main navigational directions (North, East, South, and West) found on a compass or a map.
type k	A common thermocouple sensor pairing two wires made mostly of nickel and chromium and using variance in voltage to calculate temperaturesâknown for its wide temperature range and affordabilityâtypical in industrial applications.
present movement	The best estimate of the movement of the center of a tropical cyclone at a given time and given position
bit	Abbreviation for binary digit
black-bulb thermometer	A thermometer whose sensitive element has been made to resemble a black body by covering it with lamp black
perihelion	It is the point in the Earth's orbit when it is closest to the Sun (147.5 million km)
magnetic north	See North Magnetic Pole.
input	The quantity to be measured (or modulated, or detected, or operated upon) which is received by an instrument
temperature	Measure of the energy in a substance
planetary boundary layer	Top of the planetary boundary layer; also known as depth or height of the mixing layer.
visible radiation	Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms)
carrying capacity	The steady-state density of a given species that a particular habitat can support.
antarctic	Of or relating to the area around the geographic South Pole, from 90° South to the Antarctic Circle at approximately 66 1/2°South latitude, including the continent of Antarctica
breakup	The time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow condition
kymophobia	The fear of waves.
prediction	Forecast or extrapolation of the future state of a system from current or past states.
cold	A condition marked by low or decidedly subnormal temperature
niche specialization	Process where evolution, through natural selection, adapts a species to a particular set of abiotic and biotic characteristics within a habitat.
amplitude	The magnitude of the displacement of a wave from a mean value
snow blindness	Temporary blindness or impaired vision that results from bright sunlight reflected off the snow surface
sea level	The datum against which land elevation and sea depth are measured
melting level	The altitude at which ice crystals and snow flakes melt as they descend through the atmosphere.
ecology	Science dealing with the interrelationships between livinq orqanisms and their environments.
kelvin temperature scale	A temperature scale with the freezing point of +273°K (Kelvin) and the boiling point of +373° K
grass	Type of plant that has long slender leaves that extend from a short stem or the soil surface.
convection	Vertical motion within the atmosphere due to thermal instability, with important impacts on the type cloud systems that can develop.
progradation	The natural extension of a shoreline seaward.
land breeze	a coastal breeze that blows from land out to sea, and is the result of temperature differences when the sea is warmer then the adjacent land
instream use	The use of water that does not require withdrawal or diversion from its natural watercourse; for example, the use of water for navigation, recreation, and support of fish and wildlife.
muskeg	Poorly drained marshes or swamps found overlying permafrost.
brunisol soil	Soil order (type) of the Canadian System of Soil Classification
aerosol	A system of colloidal particles dispersed in a gas (e.g., smoke or fog).
cirrostratus	They are thin, whitish cloud layers appearing like a sheet or veil
scattered	The amount of sky cover for a cloud layer between 3/8ths and 4/8ths, based on the summation layer amount for that layer.
biomaster	An anti-microbial additive to the plastic housing of some ThermoWorks products containing silver ions shown to actively inhibit bacterial growth up to 99.9% over the life of the instrument
rainshadow effect	Reduction of precipitation commonly found on the leeward side of a mountain
six's thermometer	A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time
inhibition model of succession	This model of succession suggests that the change in plant species dominance over time is caused by death and small scale disturbances and variations is plant species longevity and ability to disperse
isopleth	A line connecting equal points of value
dendrites	Thin branch-like growth of ice on the water surface.
dew-point apparatus	Same as dew-point hygrometer.
dynamics	Generally, any forces that produce motion or affect change
reference operating conditions	The range of operating conditions of a device within which operating influences are negligible
biological weathering	The disintegration of rock and mineral due to the chemical and/or physical agents of an organism.
montreal protocol	An international agreement to drastically reduce CFC production, the Protocol was adopted in Montreal in 1987
operating influence	The change in a performance characteristic caused by a change in a specified operating condition from reference operating condition, all other conditions being held within the limits of reference operating conditions.
little ice age	Time period from 1550 to 1850 AD
sulfur dioxide	A gas produced from volcanic eruptions, ocean spray, organic decomposition and the burning of fossil fuels
biome	Largest recognizable assemblage of animals and plants on the Earth
printed circuit	A fiber card on which integrated circuits and other electronic components can be mounted
law of stream lengths	Morphometric relationship observed in the cumulative size of stream segment lengths in stream channel branching
ionosphere	A complex atmospheric zone of ionized gases that extends between 50 and 400 miles (80 to 640 kilometers) above the earth's surface
skyhook balloon	A large plastic constant-level balloon for duration flying at very high altitudes.
weight barometer	A mercury barometer which measures atmospheric pressure by weighing the mercury in the column or cistern.
quantitative precipitation forecast	A forecast of rainfall, snowfall or liquid equivalent of snowfall.
sunshine	airflow, humidity, pressure and rainfall.
gradient wind	A steady horizontal air motion along curved parallel isobars or contours in an unchanging pressure or contour field, assuming there is no friction and no divergence or convergence.
marine rainbow	A rainbow seen in the spray of the ocean
wind shift line	A long, but narrow axis across which the winds change direction (usually veer).
science	Science is a way of acquiring knowledge
galaxy	An assemblage of millions to hundreds of billions of stars.
hydraulic grade line	A line whose plotted ordinate position represents the sum of pressure head plus elevation head for the various positions along a given fluid flow path, such as along a pipeline or a ground water streamline.
halo	The ring of light that seems to encircle the sun or moon when veiled by cirrus clouds
signal conditioning	The processing of the form or mode of a signal so as to make it intelligible to, or compatible with, a given device.
international index numbers	A system of designating meteorological observing stations by number, established and administered by the World Meteorological Organization
cumulus congestus	Same as towering cumulus
coupled system	Two or more processes that affect one another.
hyetograph	A graphical representation of rainfall intensity with respect to time.
chemical reaction	Reaction between chemicals where there is a change in the chemical composition of the elements or compounds concerned.
patterned ground	Term used to describe a number of surface features found in periglacial environments
baud	A unit of signaling speed representing the number of code elements sent per second; often, bits per second.
translucent	Not transparent, but clear enough to allow light to pass through.
bipolar	The ability of a panel meter to display both positive and negative readings.
lux	A photometric unit of illuminance or illumination equal to one lumen per square meter.
theodolite	An optical instrument used to track the motion of a pilot balloon, or pibal, by measuring the elevation and azimuth angles.
fsk	Frequency Shift Keying
frequency division multiplexing	The combining of a number of signals to share a medium by dividing it into different frequency bands for each signal
terminal	A generic term for any machine that enables a human being to communicate with a computer.
front	A boundary between two different air masses
snow roller	The product of moist, cohesive snow that when initiated by wind rolls across the landscape, gathering snow until it can no longer move
drawdown	The lowering of the surface elevation of a body of water, the water surface of a well, the water table, or the piezometric surface adjacent to the well, resulting from the withdrawl of water therefrom.
data object description	The basic information, definitions, and metadata required to process "raw" measurement data to standard NetCDF files.
chinook wind	The name of a North American wind that occurs on the leeward side of mountains
unstable equilibrium	In an unstable equilibrium the system returns to a new equilibrium after disturbance.
eddy diffusion	Mixing of the atmosphere by chaotic air currents.
freezing rain	Rain that falls in liquid form but freezes upon impact to form a coating of glaze on the ground and on exposed objects.
greenhouse gas	A gaseous component of the atmosphere contributing to the greenhouse effect
unstable atmosphere	Condition in the atmosphere where isolated air parcels have a tendency to rise
linearity	The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve
capillary action	Movement of water along microscopic channels
crepuscular rays	Contrasting, alternating bright and dark rays in the sky
bathythermograph	A device for obtaining a record of temperature against depth (strictly speaking pressure) in the upper 300 meters of the ocean from a ship underway
flocculation	Chemical processes where salt causes the aggregation of minute clay particles into larger masses that are too heavy to remain suspended water.
solar day	The complete rotation of the earth in relation to the sun
mean sea level	The average height of the sea surface water level
earthquake focus	Point of stress release in an earthquake.
broken	The amount of sky cover for a cloud layer between 5/8ths and 7/8ths, based on the summation layer amount for that layer.
element	A molecule composed of one type of atom
water	liquid or solid, derived from the atmosphere that falls to the earth's surface
interference	Form of competition where an individual directly prevents the physical establishment of another individual in a portion of a habitat.
mixing	Air movements (usually vertical) that make the properties of the air with a parcel homogeneous
equatorial trough	The quasi-continuous area of low pressure between the subtropical high pressure areas in both the Northern and Southern Hemisphere.
fractus	The elements of cumulus and stratus clouds that appear in irregular fragments, as if they had been shred or torn
resource	Anything obtained from the environment to meet the needs of a species.
magnetometer	General name for an instrument which measures the earth's magnetic field intensity.
subtropical	The region between the tropical and temperate regions, an area between 35° and 40° North and South latitude
eddy	Swirling air currents that varies from the main air current.
floodproofing	The process of protecting a building from flood damage on site
wind run	The distance or length of flow of the air past a point during a given interval of time.
moho discontinuity	The lower boundary of the crust
helium	An inert gas
trade winds	Surface winds that generally dominate air flow in the tropics
backwater flooding	Upstream flooding caused by downstream conditions such as channel restriction and/or high flow in a downstream confluence stream.
calorie	The amount of heat needed to raise the temperature of one gram of water at 15 degrees centigrade one degree centigrade
saturation point	at the same temperature, and is usually expressed as a percentage; i.e.
calibration	The process whereby a position on the scale of an instrument is identified with the magnitude of the signal (or input force) actuating the instrument.
primary consumer	Organisms that occupy the second trophic level in the grazing food chain
environment	The complex of physical, chemical, and biological factors in which a living organism or community exists.
satellite images	Images taken by a weather satellite that reveal information, such as the flow of water vapor, the movement of frontal system, and the development of a tropical system
primary pollutant	Air pollutants that enter the atmosphere directly
primary producer	Organisms that occupy the first trophic level in the grazing food chain
meteoric water	Water derived from precipitation.
steady state equilibrium	In this type of equilibrium the average condition of the system remains unchanged over time.
percolation path	The course followed by water moving or percolating through any other permeable material, or under a dam which rests upon a permeable foundation.
orographic lifting	Occurs when air is forced to rise and cool due to terrain features such as hills or mountains
vertical aerial photograph	Photograph taken from a overhead or near overhead angle from a platform in the atmosphere.
outlet	An opening through which water can be freely discharged from a reservoir.
water vapor	Water in a gaseous form.
productivity	Rate of energy fixation or storage of biomass by plants
phot	A photometric unit of illuminance or illumination equal to one lumen per square centimeter.
wind speed	The rate of the motion of the air on a unit of time
mouth	End of a stream
non-renewable resource	Resource that is finite in quantity and is being used faster than its ability to regenerate itself.
diffraction	The bending of light around objects, such as clouds and fog droplets, producing fringes of light and dark colored bands.
glaciofluvial	Geomorphic feature whose origin is related to the processes associated with glacial meltwater.
pluton	Any mass of intrusive igneous rock.
river statement	A NWS product issued to communicate notable hydrologic conditions which do not involve flooding, i.e., within river bank rises, minor ice jams, etc.
infiltration	Movement of water through the soil surface into the soil
inceptisols	Soil order (type) of the United States Natural Resources Conservation Service Soil Classification System
teleconnection	A strong statistical relationship between weather in different parts of the globe
gray body	A hypothetical body which absorbs some constant fraction, between zero and one, of all electromagnetic radiation incident upon it, which fraction is the absorptivity and is independent of wavelength
mitochondria	Organelle in a cell that oxidizes organic (see respiration) energy for use in cellular metabolism.
inlay	decorative designs made by cutting patterns into the wood of an instrument & filling the cut-out with contrasting wood, abalone, mother-of-pearl, metal or other aesthetically pleasing materials.
holosteric barometer	Same as aneroid barometer
shear	It is the rate of change over a short duration
glacial valley	Valley that was influenced by the presence of glaciers
strike	One of the directional properties of a geologic structure such as a fold or a fault
invertebrate	Animal that does not have a backbone
visual range	The maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.
wefax	See weather facsimile.
backshore	Area behind the shore
köppen climate classification	System that uses monthly precipitation and temperature data and total annual precipitation data to classify a location's climate into one of five main categories: Tropical Moist Climates; Dry Climates; Moist Mid-latitude Climates with Mild Winters; Moist Mid-Latitude Climates with Cold Winters; and Polar Climates
nivation hollow	Ground depression found in periglacial areas that is created by nivation.
gravitation	The mutual attraction between two masses of matter
hadley cell	Three-dimensional atmospheric circulation cell located at roughly 0 to 30° North and South of the equator
rms	Root Mean Square
prevailing wind	Dominant direction that a wind blows from for a location or region.
illuminance	The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.
thermodynamic equilibrium	This type of equilibrium describes a condition in a system where the distribution of mass and energy moves towards maximum entropy.
entrainment	The mixing of environmental air into a preexisting air current or cloud so that the environmental air becomes part of the current or cloud.
transparent	A condition where a material is clear enough not to block the passage of radiant energy, especially light.
biotite	Rock forming mineral of the mica group.
water vapor path	A measure of the total amount of water vapor present in the column
true wind direction	The direction, with respect to true north, from which the wind is blowing
li	An acronym for Lifted Index.
chocolatta north	A West Indian gale that blows from the northwest.
southern oscillation	Reversal of atmospheric circulation in tropical Pacific Ocean that triggers the development of an El Ni隳.
frontolysis	The process in which a front dissipates
deposition	A process that occurs in subfreezing air when water vapor changes directly to ice without becoming a liquid first.
bimetallic thermometer	A thermometer, the sensitive element of which consists of two metal strips which have different coefficients of expansion and are brazed together
international date line	A line drawn almost parallel to the 180 degree longitude meridian that marks the location where each day officially begins
radiation	Emission or transfer of energy in the form of electromagnetic waves or particles.
sill	Horizontal planes of igneous rock that run parallel to the grain of the original rock deposits.They form when magma enters and cools in bedding planes found within the crust
beach	The terrestrial interface area in between land and a water body where there are accumulations of unconsolidated sediments like sand and gravel
neutral stability	An atmospheric condition that exists in unsaturated (saturated) air when the environmental lapse rate equals the dry (moist) adiabatic rate.
rock	A compact and consolidated mass of mineral matter
one-tailed statistical test	Is an inferential statistical test where the values for which one can reject the null hypothesis are located entirely in one side of the center of the probability distribution.
synoptic view	The ability to see large areas at the same time.
ecology	The study of the relationships between living organisms and their environment.
calibration bath	A uniform temperature enclosure using carefully stirred fluid to provide excellent thermal contact and uniformity for temperature calibration.
fundamental niche	Describes the total range of environmental conditions that are suitable for a species existence without the effects of interspecific competition and predation from other species.
steam fog	It forms as cold air moves over warm water
haze	Fine dry or wet particles of dust, salt, or other impurities that can concentrate in a layer next to the Earth when air is stable.
distributary	A smaller branching stream channel that flows away from a main stream channel
primary carnivore	See secondary consumer.
parasitic element	See antenna.
drainage wind	A katabatic wind, it is caused by the cooling of air along the slopes of a mountain.
wetting and drying	Physical weathering process where rocks are mechanically disintegrated by the accumulation of successive layers of water molecules in between the mineral grains of a rock
isotach	A line on a weather map or chart connecting points where winds of equal speeds have been recorded.
cross section	See radar cross section.
tropical savanna	See savanna.
squall	A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.
basic solution	Any water solution that is basic (pH greater than 7) or has less hydrogen ions (H+) than hydroxide ions (OH-)
seepage	The interstitial movement of water that may take place through a dam, its foundation, or abutments.
station elevation	The vertical distance above mean sea level that is the reference level for all current measurements of atmospheric pressure at that station.
condensation	Condensing ; condensed material (esp
snow banner	A plume of snow blown off a mountain crest, resembling smoke blowing from a volcano.
solonetzic soil	Soil order (type) of the Canadian System of Soil Classification
impulse	See upper level system.
cryophobia	Fear of extreme cold, ice, or frost.
freezing	The change in state of matter from liquid to solid that occurs with cooling
centroid	The center of mass of a convective cell (storm) or other precipitation system.
experiment	A controlled investigation designed to evaluate the outcomes of causal manipulations on some system of interest.
wind	Air in motion relative to the surface of the earth
scientific method	The approach science uses to gain knowledge
surface water	Water that flows in streams and rivers and in natural lakes, in wetlands, and in reservoirs constructed by humans.
frictional force	Force acting on wind near the Earth's surface due to frictional roughness
neutral	Any substance with a pH around 7.
glacial trough	A deep U-shaped valley with steep valley walls that was formed from glacial erosion
pyroxene	A group of single chained inosilicate minerals whose basic chemical unit is the silica tetrahedron (SiO4)
cold glacier	Glacier in which the ice found from the its surface to base has a temperature as cold as -30° Celsius throughout the year
bearing	The combination of antenna azimuth and elevation required to point (aim) an antenna at a spacecraft
tide gauge	A device for measuring the height of tide
physical climate system	The system of processess tht regulate climate, including atmospheric and ocean circulation, evaporation and percipitation.
diversion	The taking of water from a stream or other body of water into a canal, pipe, or other conduit.
receiver	The electronic device which detects the backscattered radiation, amplifies it and converts it to a low-frequency signal which is related to the properties of the target.
mesoscale	Size scale referring to weather systems smaller than synoptic-scale systems but larger than storm-scale systems
meander	Sinuous shaped stream channel
exfoliation dome	A physical weathering feature associated with granite that is the result of the erosion of overburden material and pressure-release
watershed	The total area drained by a river and its tributaries
superrefraction	Bending of the radar beam in the vertical which is greater than sub-standard refractive conditions
bit	A contraction of "binary digit." The basic element of a two-element (binary) computer language.
heat wave	A period of abnormally and uncomfortably hot weather
speciation	The process by which new species originate through mutations, natural selection, and evolution.
glacial polish	The abrasion of bedrock surfaces by materials carried on the bottom of a glacier
paleoclimate	Climate as it existed in the distant past, particularly before historical records.
barometric altimeter	Same as pressure altimeter.
recurrence interval	The average amount of time between events of a given magnitude
cloud seeding	An experimental process used to weaken hurricanes or make rain in dry areas.
cloud layer	An array of clouds whose bases are at approximately the same level.
sand	Loose particles of hard, broken rock or minerals
metadata	Information describing the content or utility of a data set
plagioclase feldspar	A type of feldspar that is rich in sodium and calcium
erosion	The movement of soil or rock from one area to another by the action of the sea, running water, moving ice, precipitation, or wind.
spectrohelioscope	Similar to the spectroheliograph, but used for visual instead of photographic purposes.
wild fence	A wooden enclosure about sixteen feet square and eight feet high with a precipitation gauge at its center
aquifer	Layer of water-bearing permeable rock, sand, or gravel capable of providing significant amounts af water
rock cycle	General model describing the geomorphic and geologic processes involved in the creation, modification and recycling of rocks.
supercooling	The reduction of the temperature of any liquid below the melting point of that substance's solid phase
inch of mercury	A common unit used in measurement of atmospheric pressure
firn	Névé on a glacier that survives the year's ablation season
isodrosotherm	The line drawn on a weather map connecting points of equal dew point.
continental crust	Granitic portion of the Earth's crust that makes up the continents
photometer	Any of a number of atmospheric phenomena which appear as luminous patterns in the sky
precipitation-evaporation index	Same as precipitation-effectiveness index.
bowen ratio	The ratio of energy available for sensible heating to energy available for latent heating.
funnel cloud	A violent, rotating column of air visibly extending from the base of a towering cumulus or cumulonimbus toward the ground, but not in contact with it
sediment storage capacity	The volume of a reservoir planned for the deposition of sediment.
twilight	Often called dusk, it is the evening period of waning light from the time of sunset to dark
natural ionizing radiation	Ionizing radiation that comes from natural sources in the environment.
percolation deep	In irrigation or farming practice, the amount of water that passes below the root zone of the crop or vegetation.
environment	The sum total of all the external conditions that effect an organism, community, material, or energy.
ferrel cell	Three-dimensional atmospheric circulation cell located at roughly 30 to 60° North and South of the equator.
aleutian low	A semi-permanent, subpolar area of low pressure located in the Gulf of Alaska near the Aleutian Islands
plankton	Minute plant (phytoplankton) and animal organisms (zooplankton) that are found in aquatic ecosystems.
trajectory	The curve that a body, such as a celestial object, describes in space
tilt	It describes a storm in which a line connecting the centroid of a mid level storm component to the centroid of the lowest storm component is to the right or the rear of the direction of motion.
lateral moraine	Moraine that is found along the sides of a glacier
iceberg	A mass of ice found floating in the ocean or a lake
ifr	Abbreviation for Instrument Flight Rules, but commonly used to refer to the weather and/or flight conditions to which these rules apply, i.e
humidity	Water vapor content of the air
industrial revolution	Major change in the economy and society of humans brought on by the use of machines and the efficient production of goods
mtbf	Abbreviation for mean time between failures.
conduction	The transfer of heat from one substance to another by direct contact
spatial isolation	Reproductive isolation of two or more populations of a species by distance or physical barriers
zephyr	A Mediterranean term for any soft, gentle breeze.
system	A system is a set of interrelated components working together towards some kind of process.
indian summer	A warm, tranquil spell of weather in the autumn, especially after a period of cold weather
compensation of instruments	The use of electromechanical devices to reduce (compensate for) the sensitivities of meteorological sensors to other parameters (e.g., the effect of temperature on a pressure sensor).
maunder minimum	Period from 1645 to 1715 during which the Sun had very little sunspot activity.
threshold	The level of magnitude of a system process at which sudden or rapid change occurs.
hail	snow and sleet
patches	Used with fog to denote random occurrence over relatively small areas.
spodosols	Soil order (type) of the United States Natural Resources Conservation Service Soil Classification System
superrefraction	Greater than normal bending of light or radar beam as it passes through a zone of contrasting properties, such as atmospheric density, water vapor, or temperature.
carbon-film hygrometer element	An electrical hygrometer element constructed of a plastic strip coated with a film of carbon black dispersed in a hygroscopic binder
funnelling	The process whereby wind is forced to flow through a narrow opening between adjacent land areas, resulting in increased wind speed.
gram	A c.g.s
mar	Modernization and Associated Restructuring of the NWS.
sunrise	The daily appearance of the sun on the eastern horizon as a result of the earth's rotation
water table	Top surface of groundwater.
nutrient	Any food, chemical element or compound an organism requires to live, grow, or reproduce.
real-time	The actual time during which physical events take place.
continent	A large land mass rising abruptly from the deep ocean floor, including marginal regions that are shallowly submerged
representative fraction	The expression of map scale as a mathematical ratio.
lee wave	A wave disturbance in airflow due to some barrier in the flow, i.e
lithometeor	The general term for dry atmospheric suspensoids, including dust, haze, smoke, and sand
meteorogram	A record obtained from a meteorograph
venturi tube	A tube designed to measure the rate of flow of fluids
accuracy	"The closeness of the agreement between the result of a measurement and the value of the quantity being measured and or ""true value."" Usually expressed as Â± a certain number of degrees or Â± a certain percentage of the full reading."
geographic range	Spatial distribution of a species
playa	A dry lake bed found in a desert.
global warming	An overall increase in world temperatures which may be caused by additional heat being trapped by greenhouse gases.
barogram	The record of a barograph.
effective radar reflectivity factor	See Equivalent Radar Reflectivity Factor.
ppt	See parts per thousand.
nansen bottle	A device used by oceanographers to obtain subsurface samples of sea water
ram penetrometer	A cone-tipped metal rod designed to be driven downward into deposited snow or firn
gravel	A term used to describe unconsolidated sediments composed of rock fragments
binary	A numbering system that uses only 1 and 0 (e.g., 1 is one, 10 is two, 11 is three)
rs485	A protocol similar to RS232 which permits data interchange on multidrop networks of up to 32 nodes using a single twisted pair cable
thermal low	Also known as heat low, it is an area of low pressure due to the high temperatures caused by intensive heating at the surface
kirchoff's law	This law suggests that good emitters of radiation are also good absorbers of radiation at specific electromagnetic radiation wavelength bands
confluence	A rate at which wind flow comes together along an axis oriented normal to the flow in question
ring of fire	See Circum-Pacific Belt.
repeatability	The closeness of agreement among a number of consecutive output values measuring the same input value under the same operating conditions, approaching from the same direction
prevailing visibility	It is considered representative of visibility conditions at the observation station
upper level system	A general term for any large-scale or mesoscale disturbance capable of producing upward motion (lift) in the middle or upper parts of the atmosphere
radio theodolite	An instrument for determining the direction from which radio waves approach a receiver
snow grains	Precipitation of very small, white, opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm
cyclogenesis	Process of cyclone formation, maturation, and death.
undercurrent	A current below the upper currents or surface of a fluid body.
swell	Wind-generated waves that have traveled out of their generating area
free balloon	A buoyant balloon rising freely in the atmosphere, as opposed to a captive balloon.
wind passage	The distance or length of flow of the air past a point during a given interval of time.
output	Movement of matter, energy, or information out of a system
telethermoscope	A temperature telemeter.
sling psychrometer	An instrument used to measure the water vapor content of the atmosphere, which wet and dry bulb thermometers are mounted on a frame connected to a handle at one end by means of a bearing or a length of chain
x-rays	Very energetic electromagnetic radiation with wavelengths intermediate between 0.01 and 10 nanometers (0.1-100 Angstroms) or between gamma rays and ultraviolet radiation
pluvial index	The amount of precipitation falling in one day, or other specified period, that is likely to be equalled or exceeded in any given place only once in a century
thermocline	A vertical negative temperature gradient in some layer of a body of water which is appreciably greater than the gradients above and below it
o horizon	Topmost layer of most soils
greenhouse gases	Gases responsible for the greenhouse effect
milky way galaxy	Aggregation of about 400 billion stars in a flattened, disk-shaped structure in space
regolith	Loose layer of rocky material overlying bedrock.
longshore current	A water current that moves parallel to the shoreline.
fahrenheit	The temperature scale on which the freezing point is 32 and the boiling point is 212 degrees.
secondary pollutant	Atmospheric pollutants that are created chemically in the atmosphere when primary pollutants and other components of the air react
sar	See synthetic aperture radar.
adiabat	A line on a thermodynamic chart relating the pressure and temperature of a substance (such as air) that is undergoing a transformation in which no heat is exchanged with its environment.
coronagraph	An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.
moraine	A hill of glacial till deposited directly by a glacier.
starch	Complex carbohydrate composed of thousands of glucose units
sbcape	CAPE calculated using a Surface based parcel.
river system	All of the streams and channels draining a river basin.
high pressure	absolute humidityThe mass of water vapor in a given volume.absolutely stable airAn atmospheric condition that exists when the environmental lapse rate is less than the moist adiabatic lapse rate.
pumping head	Energy given to a fluid by a pump, usually expressed in feet of fluid (foot pounds per pound).
lahar	A very rapid type of downslope mass movement that involving mudflows from volcanic ash.
inches of runoff	The volume of water from runoff of a given depth over the entire drainage basin.
smog	Generic term used to describe mixtures of pollutants in the atmosphere
capping inversion	An elevated inversion layer that caps a convective boundary layer, keeping the convective elements from rising higher into the atmosphere.
millibar	A unit of pressure which directly expresses the force exerted by the atmosphere
sheetwash	The removal of loose surface materials by overland flow
heterogeneity	State of being dissimilar or diverse.
control point	The temperature at which a system is to be maintained.
windward side	The side of an object that is facing into the direction that the wind is coming from.
ridge	Its an elongated area of high pressure.
light icing	The rate of ice accumulation that may create a problem if the flight is prolonged in this environment (over one hour)
back-building thunderstorm	A thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain stationary or propagate in a backward direction.
talik	An unfrozen section of ground found above, below, or within a layer of discontinuous permafrost
water-flow pyrheliometer	An absolute pyrheliometer, developed by C.G
rtd	Resistance Thermometer Detection probes use variance in resistance (typically in platinum) to calculate temperaturesâknown for high accuracy over a wide range of temperatures and low driftâtypical in high-precision applications like calibration.
solar energy	See insolation.
pressure gradient	The amount of pressure change occurring over a given distance.
centimeter-gram-second system	A system of physical units based on the use of the centimeter, gram, and the second as elementary quantities of length, mass, and time.
nitrogen saturation	Over abundance of nitrogen in natural ecosystems because of human induced inputs related to agriculture and fossil fuel combustion.
closed low	A region of low pressure distinguished by a center of counterclockwise circulation (in the Northern Hemisphere), and is surrounded by one or more isobars or height contours
hydrologic cycle	The pathways through which water is cycled in the terrestrial biosphere.
spot ratio	See Distance to Target Ratio.
temperature inversion	An extremely stable air layer in which temperature increases with altitude, the inverse of the usual temperature profile in the troposphere.
cooling-power anemometer	The general term for anemometers operating on the principle that the heat transfer to air from an object at an elevated temperature is a function of the air speed
non-ionizing radiation	A form of electromagnetic radiation that does not have enough energy to cause ionization of atoms in living tissue
snow advisory	This product is issued by the National Weather Service when a low pressure system produces snow that may cause significant inconveniences, but do not meet warning criteria and if caution is not exercised could lead to life threatening situations
dew point front	A narrow zone (mesoscale feature) of extremely sharp moisture gradient and little temperature gradient
reef	A ridge of rocks found in the tidal zone along a coastline
swell	A relatively smooth ocean wave that travels some distance from the area of its generation.
workstation	A "smart" computer terminal that serves as a primary scientific research tool, offering direct access to experimental apparatus, information files, internal computers, and output devices, usually connected to an external communications network.
ir	An acronym for Infrared
sensor calibration	The relationship between input and output for a given measurement.
quality-assured data	Typically, the final form of data to be submitted to the ARM data system
bandpass filter	A filter whose frequencies are between given upper and lower cutoff values, while substantially attenuating all frequencies outside these values (this band).
population parameter	A value used to represent a certain quantifiable characteristic of a population
radioactive decay	Natural decay of the nucleus of an atom where alpha or beta particle and/or gamma rays are released at a fixed rate.
meteorograph	An instrument which automatically records the measurement of two or more meteorological elements.
potential vorticity	This plays an important role in the generation of vorticity in cyclogenesis, especially along the polar front
snow melt	Conversion of snow into runoff and groundwater flow with the onset of warmer temperatures.
mediterranean scrubland	See chaparral.
visibility	The greatest distance that is possible for a person to see with their eyes
rain shadow	Areas of the leeward side of a mountain or mountain range which often receive much less rain than the windward side.
ablation	Depletion of snow and ice by melting and evaporation.
fresh water	Water that is relatively free of salts.
stable equilibrium	In a stable equilibrium the system displays tendencies to return to the same equilibrium after disturbance.
siltstone	Fine grained sedimentary rock composed of lithified silt particles.
vertebrate	Animal that does have a backbone
precipitable water	Total amount of water vapor in a vertical column of air, often expressed as the depth of the layer of water that would be formed if all the water vapor were condensed to liquid water.
jetty	A structure (e.g.; a pier, or mole of wood or stone) extending into a sea, lake, or river to influence the current or tide or to protect a harbor.
diploid	Cell that contains two sets of chromosomes
microprocessor	A small, limited-capacity central processing unit contained entirely on one semiconductor chip.
coral reef	Ridge of limestone found generally below the ocean surface
wave cyclone	See mid-latitude cyclone.
updraft	Upward movement of air.
eos	See Earth Observing System.
river basin	The total area drained by a river and its tributaries
pressure tendency	The character and amount of atmospheric pressure change during a specified period of time, usually 3-hour period preceding an observation.
eddy velocity	Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval
climatology	Science dealing with climate and climate phenomena.
aspect ratio	The ratio of image width to image height
downpour	A heavy rain.
lowland flooding	Inundation of low areas near the river, often rural, but may also occur in urban areas.
capillary zone	The soil area just above the water table where water can rise up slightly through the cohesive force of capillary action
ideal gas laws	The thermodynamic laws applying to perfect gases.
external forcing	Influence on the Earth system (or one of its components) by an external agent such as solar radiation or the impact of extraterrestrial bodies such as meteorites.
invof	An acronym for "in vicinity of".
pibal	Contraction for pilot balloon observation.
tide	The periodic rising and falling of the earth's oceans and atmosphere
ion	Atom or molecule that has acquired an electric charge by the loss/gain of one or more electrons.
drainage divide	The boundary line, along a topographic ridge or along a subsurface formation, separating two adjacent drainage basins.
heel	the part of an instrument’s neck that widens into an L-shaped extension where the neck and body join.
salt marsh	Coastal wetland ecosystem that is inundated for some period of time by seawater
shower	a brief period of precipitation
type t	A more specialized thermocouple sensor pairing two wires made mostly of copper and constantan and using variance in voltage to calculate temperaturesâknown for greater accuracy and durabilityâtypical in medical or pharmaceutical applications.
salinometer	Any device or instrument for measuring salinity, especially one based on electrical conductivity methods.
absolute zero	Considered to be the point at which theoretically no molecular activity exists or the temperature at which the volume of a perfect gas vanishes
coastal zone	Relatively nutrient-rich, shallow part of the ocean that extends from the high-tide mark on land to the edge of the continental shelf.
international space year	(1992) Designated the first international celebration of humanity's future in the space age
d-value	The deviation of actual altitude along a constant pressure surface from the standard atmosphere altitude of that surface.
tropical disturbance	A moving area of thunderstorms in the Tropics that maintains its identity for 24 hours or more.
flux	The rate of transfer of fluids, particles or energy per unit area across a given surface.
p.t.u.	Abbreviation for the pressure, temperature, and humidity data obtained by a radiosonde observation.
mistbow	Same as fogbow.
warm front	The boundary between two air masses, one cool and the other warm, moving so that the warmer air replaces the cooler air.
shield volcano	Volcano created from alternate layers of lava flows
central pressure	The atmospheric pressure at the center of a high or low
beam width	The angular width of the radar beam
hydrostatic pressure	Force caused by water under pressure.
radiosonde	An instrument carried through the air by a balloon
flight forecast	An aviation weather forecast for a specific flight.
sexual reproduction	Any process of reproduction that does involve the fusion of gametes.
proton	A sub-particle of an atom that contains a positive charge.
biosphere	Part of the Earth system in which life can exist, between the outer portion of the geosphere and the inner portion of the atmosphere.
nitrate	Form of nitrogen commonly found in the soil and used by plants for building amino acids, DNA and proteins
ogee	A reverse curve, shaped like an elongated letter S
hydrometeor	A general term for atmospheric water in any of its forms, i.e
drainage area	The size of the area comprising a watershed or river basin
dredging	The scooping, or suction of underwater material from a harbor, or waterway
wien's law	One of the radiation laws which states that the wavelength of maximum radiation intensity for a black body is inversely proportional to the absolute temperature of the radiating black body.
closed basin lake flooding	Flooding that occurs on lakes with either no outlet or a relatively small one
s-wave	A seismic wave that moves material it encounters perpendicular to its direction of travel
p-wave	A seismic wave that moves material in push-pull fashion in the direction of its travel
fracture zone	An area which has a great number of fractures.
easting	First measurement of a grid reference used to specific the location of a point on a rectangular coordinate system
advection fog	Fog that forms as warmer, moist air moves over a cold ground
effective porosity	The ratio, usually expressed as a percentage, of the volume of water or other liquid which a given saturated volume of rock or soil will yield under any specified hydraulic condition, to the given volume of soil or rock.
diabatic process	Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system
freons	See chlorofluorocarbons.
electromotive force	The force that can alter the motion of electricity, measured in terms of the energy per unit charge imparted to electricity passing through the source of this force
hardware	The electrical and mechanical components of a system, as opposed to software.
character	Part of a computer word that has meaning in itself; often, a byte.
digital image	An analog image converted to numerical form so that it can be stored and used in a computer The image is divided into a matrix of small regions called picture elements or pixels
hot spot	A volcanic area on the surface of the Earth created by a rising plume of magma.
haze	A suspension of fine dust and/or smoke particles in the air
thalweg	Line of deepest water in a stream channel as seen from above
gram-molecule	See mole.
biosphere	The transition zone between the earth and the atmosphere within which most terrestrial life forms are found
lipid	Is an organic compound composed of carbon atoms that have two hydrogen atoms attached
evaporation rate	The volume of liquid water evaporated per unit area in unit time, usually measured as the depth of liquid water lost per unit time from the whole area.
monsoon	a seasonal change in wind direction bringing dry air or heavy rain
sea-floor spreading	The process of oceanic crust creation and sea-floor movement that occurs at the mid-oceanic ridge.
mesocyclone	A cylinder of cyclonically flowing air that form vertically in a severe thunderstorm
upwelling	The movement of nutrient-rich deep seawater to the ocean's surface.
eclipse	The obscuring of one celestial body by another.
reg	A rocky desert landscape
liana	Species of plant that uses the support of wood plants to elevate its leaves above the forest canopy.
ocean basin	Part of the Earth's outer surface that is comprised of the ocean floor, mid-oceanic ridges, continental rise, and continental slope
isobaric process	Any thermodynamic change of state of a system that takes a place at constant pressure.
urban heat island	The increased air temperatures in urban areas in contrast to cooler surrounding rural areas.
*tower	(Short for towering cumulus), a cloud element showing appreciable upward vertical development.
eddy	A small rotating area of water.
flash flood	A flood that rises and falls quite rapidly with little or no advance warning, usually as the result of intense rainfall over a relatively small area
negative feedback	Change in the state of a system that counteracts the measured effect of the initial alteration.
depression	In meteorology, it is another name for an area of low pressure, a low, or trough
snow level	The elevation in mountainous terrain where the precipitation changes from rain to snow, depending on the temperature structure of the associated air mass.
bright band	The enhanced layer of radar echo caused by the difference in radar reflectivity of ice and water particles
recession constant	Constant used to reduce the API value daily in the API method of estimating runoff.
dissociation	Chemical process where a compound or molecule breaks up into simpler constituents.
gross sediment transport	The total amount of sediment transported along a shoreline in a specific time period.
controller	A device that regulates the power supply to a heater or bath to bring it up to a specified temperature.
simplex	Operation mode of a communication circuit in which one end can only transmit and the other end can only receive.
mosaic	A composite picture built up from a number of image segments
atoll	A coral island consisting of a ring of coral surrounding a central lagoon
centrifugal force	The apparent force in a rotating system that deflects masses radially outward from the axis of rotation
composites	Plants of the compositae family (Asteraceae)
ceiling light	A type of cloud height indicator which uses a searchlight to project vertically a narrow beam of light onto the cloud base
ice	Frozen form of the water molecule
bus	A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.
sounding	Same as an upper air observation, but commonly used to refer to a single complete radiosonde observation.
barotropy	The state of a fluid in which surfaces of constant density or temperature are coincident with surfaces of constant pressure
cumulus mediocris	Cumulus clouds characterized by moderate vertical development with upper protuberances not very marked in appearance
boyle's law	When the temperature is held constant, the pressure and density of an ideal gas are directly proportional.
lignite	Low grade coal
pitot tube	An instrument for measuring the relative speed of a fluid
scale	The array of indicating marks and figure in relation to which the position of an index is observed, i.e
cavitation	Process of intense erosion due to the surface collapse of air bubbles found in constricted rapid flows of water
sun	Its responsible for most of the earth's weather, even though it is 93 million miles away
regional metamorphism	Large scale metamorphic modification of existing rock through the heat and pressure of plutons created at tectonic zones of subduction.
process study	An organized, systematic investigation of a particular process designed to identify all of the state variables involved and to establish the relationships among them
secondary succession	Succession on a previously vegetated surface
hyetal	Of or pertaining to rain.
hydraulic radius	The right cross-sectional area of a stream of water divided by the length of that part of its periphery in contact with its containing conduit; the ratio of area to wetted perimeter
relative humidity	The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature
thaw	To free something from the binding action of ice by warming it to a temperature above the melting point of ice
fen	A habitat composed of woodland and swamp.
townsend support	A fixed support for mounting maximum and minimum thermometers of the liquid-in-glass type
thermometer support	A device used to hold liquid-in-glass maximum and minimum thermometers in the proper recording position inside an instrument shelter, and to permit them to be read and reset
soil organic matter	Organic constituents of soil.
collada	A strong, steady wind blowing from the north or northwest in the upper part of the Gulf of California and from the northeast in the lower part.
bookmatch	a method of cutting a single piece of wood through its thickness to make two pieces that have mirror-image grain pattern
dusk	The period of waning light from the time of sunset to dark.
rotation	Process of the Earth turning on its axis
chemical energy	Energy consumed or produced in chemical reactions.
alluvium	Sediments deposited by erosional processes, usual by streams.
fossil fuel	Any hydrocarbon deposit that can be burned for heat or power, such as petroleum, coal, and natural gas.
snowfall	The rate at which snow falls, usually expressed in inches of snow depth over a six hour period.
flood plain	Lowland, bordering a river, that is usually dry, but which is subject to flooding.
el ni隳	Name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru
lacquer	flexible & tonally responsive finishes containing cellulose (e.g
occluded front	A transition zone in the atmosphere where an advancing cold air mass sandwiches a warm air mass between another cold air mass pushing the warm air into the upper atmosphere.
climatology	Scientific study of the Earth's climate over long time spans (greater than several days)
pediment	A gradually sloping bedrock surface located at the base of fluvial-eroded mountain range
range resolution	The ability of radar to distinguish between targets on the same azimuth but at different ranges.
fertilizer	Substance that adds inorganic or organic nutrients to soil for the purpose of increasing the growth of crops, trees, or other vegetation.
tide	The regular rise and fall of the Earth's oceans caused by the actions of the moon's and sun's gravitation acting on the rotating Earth.
psychrometer	An instrument used to measure the water vapor content of the air
perigee	The point nearest the earth on the moon's orbit
sandstorm	Particles of sand carried aloft by strong wind
image	Pictorial representation of data acquired by satellite systems, such as direct readout images from environmental satellites
evaporation pan	Meteorological instrument that is used to measure evaporation rates.
operating conditions	Conditions to which a device is subjected, not including the variable measured by the device
hydrologic cycle	The succession of stages through which water passes on the ground and in the atmosphere: evaporation from land or bodies of water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.
bernoulli's theorem	A statement of the conservation of energy for a steady, nonviscous, incompressible level flow
tilt	The inclination to the vertical of a significant feature of the pressure pattern or of the field of moisture or temperature
fluvial	Involving running water
eye wall	It is an organized band of cumuliform clouds that immediately surrounds the center (eye) of a hurricane
zone of accumulation	Area of a glacier where additions of snow exceed losses of ice from melting, evaporation, and sublimation.
collector	A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.
argon	A colorless, odorless inert gas that is the third most abundant constituent of dry air, comprising 0.93% of the total.
smog	Its visible air pollution in urban areas
polar cell	Three-dimensional atmospheric circulation cell located at roughly 60 to 90° North and South of the equator
weather	The condition of the air around us.
precipitation	All liquid or solid phase aqueous particles that originate in the atmosphere and fall to the earth's surface.
s-band	One of the segments or bands into which the radio frequency spectrum above 1000 MHz is divided, designated by letters
radiation	Energy emitted in the form of electromagnetic waves
universal coordinated time	One of several names for the twenty-four hour time which is used throughout the scientific and military communities
ponding	In flat areas, runoff collects, or ponds in depression and cannot drain out
rangeland	Land-use type that supplies vegetation for consumption by grazing and browsing animals
vane	See wind vane.
scattering	The change in direction, frequency, or polarization of electromagnetic waves
podzolization	Soil forming process that produces a strongly leached soil with a distinctive iron hardpan layer in the B horizon
heterotroph	Organism that must consume energy rich organic molecules for survival
disturbance	A low pressure system, a tropical area of storminess, or any area in which the weather is in a state of cloudiness, precipitation or wind.
scattering	The process by which small particles suspended in the air diffuse a portion of the incident radiation in all directions
sunset	Moment of time when the Sun's edge completely disappears below the Earth's horizon.
old growth forest	Climax forests dominated by late successional species of trees that are hundreds to thousands of years old
groundwater flow	Underground topographic flow of groundwater because of gravity.
flyoff	The total amount of water transferred to the atmosphere by evapotranspiration.
stratiform	Descriptive of clouds of extensive horizontal development, as contrasted to the more narrow and vertically developed cumuliform type
flood loss reduction measures	The strategy for reducing flood losses
meridional flow	Large-scale atmospheric flow in which the north-south component (i.e., longitudinal, or along a meridian) is pronounced
standard error	The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.
graded stream	A stream that has a long profile that is in equilibrium with the general slope of the landscape
speed of light	Velocity of light in a vacuum
melting point	The temperature at which a solid substance undergoes fusion, changing from a solid to a liquid state
sima layer	The part of the crust that forms the ocean basins and lower layers in the crust and is composed of relatively heavy, basaltic rocks.
photoelectric cell	A transducer which converts electromagnetic radiation in the infrared, visible, and ultraviolet regions into electrical quantities such as voltage, current, or resistance
liquid	A state of matter where molecules have the ability to flow and the surface of this mass displays the property of surface tension.
irrigated area	The gross farm area upon which water is artificially applied for the production of crops, with no reduction for access roads, canals, or farm buildings.
thermogram	The record of a thermograph.
county warning area	All the counties or parishes assigned to a specific National Weather Service Forecast Office for the purpose of warnings issuance and hazard awareness responsibility.
dew point	The temperature to which air must be cooled (at constant pressure and constant water vapor content) for saturation to occur
evaporation	Evaporation can be defined as the process by which liquid water is converted into a gaseous state
seismic wave	Successive wave-type displacement of rock usually caused by an earthquake.
radiation shield	A device used on certain types of instruments to prevent unwanted radiation from affecting the measurement of a quantity
cheimaphobia	The fear of cold
wildlands	Any non-urbanized land not under extensive agricultural cultivation, e.g., forests, grasslands, rangelands.
squall	A sudden onset of strong winds with speeds increasing to at least 16 knots (18 miles per hour) and sustained at 22 or more knots (25 miles per hour) for at least one minute
observational error	The difference between the true value of some quantity and its observed value
prevailing visibility	The visibility that is considered representative of conditions at the station; the greatest distance that can be seen throughout at least half the horizon circle, not necessarily continuous.
chemical process	(chemistry) any process determined by the atomic and molecular composition and structure of the substances involved
winter storm warning	Its issued when hazardous winter weather is occurring or is likely over a specific area
pressure jump	A sudden, sharp increase in atmospheric pressure, typically occurring along an active front and preceding a storm.
recessional moraine	Moraine that is created during a pause in the retreat of a glacier
potential energy	Is the energy that a body possesses by virtue of its position and that is potentially transformable into another form of energy.
host	Organism that develops disease from a pathogen or is being feed on by a parasite.
great circle	An imaginary circle drawn on the Earth's surface that has its center synchronize to the center of the planet
fire weather	The state of the weather with respect to its effect upon the kindling and spreading of forest fires.
field	The set of influences (electricity, magnetism, gravity) that extend throughout space.
meridional flow	Its when the winds in the upper levels of the atmosphere blow from a North to South component which usually creates a buckling effect in the jet stream.
confined groundwater	Groundwater trapped between two impervious layers of rock.
shower	Precipitation from a convective cloud that is characterized by its sudden beginning and ending, changes in intensity, and rapid changes in the appearance of the sky
supercool	To cool a liquid below its freezing point without solidification or crystallization.
snowfall	precipitation falling from clouds in the form of ice crystals
evapotranspirometer	A type of lysimeter that measures the rate of evapotranspiration
phenolic	A plastic molding component formed by the reaction of phenol and formaldehyde
vernal equinox	Taking place in the Northern Hemispheric spring, it is the point at which the ecliptic intersects the celestial equator
celsius scale	Scale for measuring temperature
luminous flux	The flux of visible radiation, so weighted as to account for the manner in which the response of the human eye varies with the wavelength of radiation
biota	The plant and animal life of a region or area.
amplitude modulation	One of three ways to modify a sine wave signal in order to make it "carry" information
inclination	One of the six Keplerian elements, it indicates the angle of the orbit plane to the central body's equator.
cardinal winds	Winds from the four cardinal points of the compass; that is, north, east, south, and west winds.
ecosystem	An ecosystem is a system where populations of species group together into communities and interact with each other and the abiotic environment.
fungi	Group, at the kingdom level, in the classification of life
disturbance	A disruption of the atmosphere that usually refers to a low pressure area, cool air and inclement weather.
stratocumulus	A low cloud composed of layers or patches of cloud elements
hydrolysis	Chemical weathering process that involves the reaction between mineral ions and the ions of water (OH- and H+), and results in the decomposition of the rock surface by forming new compounds, and by increasing the pH of the solution involve through the release of the hydroxide ions.
gram-mole	See mole.
standard deviation	A statistical measure of the dispersion of observation values in a data set
mist	Water droplets so small that they are floating in the air
ansi	An acronym for American National Standards Institute
cumulus clouds	Fluffy, mid-level clouds that develop in towering shapes and signal fair weather
thermosphere	A thermal classification, it is the layer of the atmosphere located between the mesosphere and outer space
weir	a) A low dam built across a stream to raise the upstream water level (fixed-crest weir when uncontrolled); b) A structure built across a stream or channel for the purpose of measuring flow (measuring or gauging weir).
staphylococcus	A microscopic bacteria common to skin and mucous membranes
eosophobia	The fear of dawn or daylight.
telephotometer	A photometer that measures the received intensity of a distance light source.
ozone layer	The layer of ozone that begins approximately 15 km above Earth and thins to an almost negligible amount at about 50 km, shields the Earth from harmful ultraviolet radiation from the sun
ceiling light	An instrument consisting of a drum and an optical system that projects a narrow vertical beam of light onto a cloud base.
community	Refers to all the populations of interacting species found in a specific area or region at a certain time.
mode	Statistical measure of central tendency in a set of data
atmospheric infrared sounder	Advanced sounding instrument selected to fly on the EOS-PM I mission (intermediate sized, sun-synchronous, morning satellite) in the year 2000
inversion	A departure from the usual increase or decrease of an atmospheric property with altitude
kelvin	An absolute, thermodynamic temperature scale using as its null point absolute zero and the triple point of water at 273.16 K (0.01 Â°C; 32.02 Â°F)
monera	Group, at the kingdom level, in the classification of life
second-growth forest	Stand of forest that is the result of secondary succession.
chloroplast	Organelle in a cell that contains chlorophyll and produces organic energy through photosynthesis.
inorganic	Non-living thing
isoheight	Same as a contour depicting vertical height of some surface above a datum plane.
segregated ice	A form of periglacial ground ice that consists of almost pure ice that often exists as an extensive horizontal layer
arctic air mass	An air mass that develops around the Arctic, it is characterized by being cold from surface to great heights
sand ripples	Another term used for wind ripples.
conductor	Any substance or object which carries electricity.
kinetic energy	The energy due to motion.
ridge	An elongated area of relatively high pressure
carbon dioxide	Common gas found in the atmosphere
tropics	The area between 23.5 degrees north and south of the equator
maximum unambiguous range	The greatest distance a pulse can travel and return before the next pulse is transmitted
kame terrace	A long flat ridge composed of glaciofluvial sediment
summer	Season between spring and fall
bellot winds	Refers to the winds in the Canadian Arctic that blow through the narrow Bellot Strait between Somerset Island and the Boothia Peninsula, connecting the Gulf of Boothia and Franklin Strait.
endangered species	A species found in nature that has so few surviving individuals that the it could soon become extinct in all or most of its natural range
bayhead beach	An extensive deposit of sand and/or gravel in the form of a beach at the back of a bay.
river flooding	The rise of a river to an elevation such that the river overflows its natural banks causing or threatening damage.
riparian zone	A stream and all the vegetation on its banks.
loam	A soil that contains a roughly equal mixture of clay, sand, and silt
star	A large and very massive, self-luminous celestial body of gas that illuminates via the radiation derived from its internal source of energy.
rotation anemometer	A type of anemometer in which the rotation of an element serves to measure the wind
volt	The unit of electromotive force, or difference of potential, which will cause a current of one ampere to flow through a resistance of one ohm
cation exchange	Chemical trading of cations between the soil minerals and organic matter with the soil solution and plant roots.
vil	Vertically-Integrated Liquid water
gneiss	A metamorphosed coarse grained igneous rock
very high frequency	Referring to the 50-400 MHz portion of the radio frequency spectrum
warm high	A high pressure system that has its warmest temperatures at or near the center of circulation
blowing spray	Salt spray that is raised by the wind to heights of six feet or greater
continuous permafrost	Form of permafrost that exists across a landscape as an unbroken layer.
chemical weathering	Breakdown of rock and minerals into small sized particles through chemical decomposition.
isothermal process	Any thermodynamic change of state of a system that takes place at constant temperature.
biennial plant	Plant species that completes its life in two growing seasons.
hydraulic gradient	The slope of the water table or aquifer
ozone advisory	It is issued by the Department of Natural Resources (DNR) through the National Weather Service when ozone levels reach 100
dryline storm	Generally, any thunderstorm that develops on or near a dry line
eutrophication	Physical, chemical and biological changes in a water body as a result of the input nitrogen and phosphorus.
tropopause	The boundary between the troposphere and stratosphere, usually characterized by an abrupt change in lapse rate
period decay	The tendency of a satellite to lose orbital velocity due to the influence of atmospheric drag and gravitational forces
conveyance loss	The loss of water from a conduit due to leakage, seepage, evaporation, or evapotranspiration.
predator	Consumer organism who feeds on prey
eye	The relatively calm center in a hurricane that is more than one half surrounded by wall cloud
parasite	Consumer organism that feeds on a host for an extended period of time
crystal habit	The size and shape of the crystals in a crystalline solid
iflows	Integrated Flood Observing and Warning System
terminus	End or snout of a glacier.
centigrade	Temperature scale proposed by Swedish astronomer Anders Celsius in 1742
marine barometer	A mercury barometer designed for use aboard ship
temperature coefficient	(1) The ratio of the speeds of a chemical reaction at two temperatures differing by 10°C
heterosphere	The upper layer in a two part classification of the atmosphere based on the general homogeneity of chemical composition
snow	Precipitation in the form of ice crystals, mainly of intricately branched, hexagonal form and often agglomerated into snowflakes, formed directly from the freezing [deposition] of the water vapor in the air.
parapet wall	A solid wall built along the top of the dam for ornament, safety, or to prevent overtopping.
shale	Fine grained sedimentary rock composed of lithified clay particles.
deranged drainage	Drainage pattern that is highly irregular
luminous intensity	The intensity (flux per unit solid angle) of visible radiation weighted to take into account the variable response of the human eye as a function of the wavelength of light
vascular plant	Plant that has vascular tissues to transport water, nutrients, and other metabolic products.
sam	Station for Atmospheric Measurements
bed load	Portion of the stream load that is carried along the stream bed without being permanently suspend in the flowing water.
field of view	The range of angles that are scanned or sensed by a system or instrument, measured in degrees of arc.
wind direction	The direction from which the wind is blowing, measured in points of the compass or in azimuth degrees.
evaporograph	Instrument which measures and records the amount of evaporation over time.
upslope effect	The cooling of an air flow as it ascends a hill or mountain slope
spray	An ensemble of water droplets torn by the wind from the surface of the of an extensive body of water, generally from crests of waves, and carried a short distance into the air.
barrier beach	A long and narrow beach of sand and/or gravel that runs parallel to the coastline and is not submerged by the tide.
infrared satellite imagery	This satellite imagery senses surface and cloud top temperatures by measuring the wavelength of electromagnetic radiation emitted from these objects
hypothesis	A tentative assumption that is made for the purpose of empirical scientific testing
onshore-offshore transport	The up and down movement of sediment roughly perpendicular to a shoreline because of wave action.
permeability	Capacity of a soil or other surface to be penetrated by water sinking into the ground under the force of gravity
bankfull stage	An established river stage at a certain point along a river which is intended to represent the maximum safe water level which will not overflow the river banks or cause any significant damage within the reach of the river.
horizontal wind	The horizontal wind in terms of either speed and direction, or the zonal (u) and meridional (v) components.
slush	Its snow or ice on the ground that has been reduced to a soft, watery mixture by rain or warm temperatures.
tilt"	The inclination to the vertical of a significant feature of the pressure pattern or of the field of moisture or temperature
ice run	Flow of ice in a river
microscale	Pertains to meteorological phenomena, such as wind circulations or cloud patterns, that are less than 2 kilometers in horizontal extent.
high pressure system	An area of relative pressure maximum that has diverging winds and a rotation opposite to the earth's rotation
thermal	Small rising column of air due to surface heating.
flooded ice	Ice which has been flooded by melt water or river water and is heavily loaded by water and wet snow.
snow	Frozen precipitation in the form of white or translucent ice crystals in complex branched hexagonal form
potometer	A device, similar to a phytometer, for measuring transpiration
microwave	Electromagnetic radiation with wavelengths between about 1000 micrometers and one meter
gaia hypothesis	The hypothesis that the Earth's atmosphere, biosphere, and its living organisms behave as a single system striving to maintain a stability that is conducive to the existence of life.
integrated circuit	A solid state electronic circuit that consists of several micro-components constructed to perform a special function.
compound	A compound is the atoms of different elements joined together.
tsunami	Large ocean wave created from an earthquake or volcanic eruption
byte	The group of bits which a computer processes as a unit; often, 8 bits.
streamer	A channel of very high ion density which propagates through the air by the continual establishment of an electron avalanche ahead of its tip.
germination	The beginning of vegetative growth of a plant from a seed.
undercut bank	Steep bank found on the inside of stream meanders
hysteresis	A quality of a system such that the output is not only determined by the input but also by the internal state of the system, particularly as it is affected by previous measurements
eddy	A small disturbance of wind in a large wind flow, which can produce turbulent conditions
basin boundary	The topographic dividing line around the perimeter of a basin, beyond which overland flow (i.e.; runoff) drains away into another basin.
capillary potential	The work required to move a unit mass of water from the reference plane to any point in the soil column.
surface creep	The sliding and rolling movement of soil particles on the Earth's surface because of wind
isobar	Lines on a map joining points of equal atmospheric pressure.
net rainfall	The portion of rainfall which reaches a stream channel or the concentration point as direct surface flow.
stability	The ability of an instrument or sensor to maintain a consistent output when a constant input is applied over time
fish	Group of vertebrate animals that inhabit aquatic habitats.
water equivalent	The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.
psychorophobia	The fear of the cold
backscatter depolarization ratio	The ratio of cross polarized to co-polarized elastic backscatter.
gene pool	Sum total of all the genes found in the individuals of the population of a particular species.
siphon barograph	A recording siphon barometer.
density	The ratio of the mass of a substance to the volume occupied by it.
epicenter	Surface location of an earthquake's focus.
gage height	The water-surface elevation referred to some arbitrary gage datum
floating pan	An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.
runway visibility	The visibility along an identified runway, determined from a specified point on the runway with the observer facing in the same direction as a pilot using the runway
dry line	The boundary between the dry desert air mass of the Southwest U.S
normal fault	Vertical fault where one slab of the rock is displaced up and the other slab down
calving	The loss of glacier mass when ice breaks off into a large water body like an ocean or a lake.
nonsymbiotic mutualism	Mutualistic interaction where the mutualists live independent lives yet cannot survive without each other
boiling point	The temperature at which a substance in the liquid phase transforms to the gaseous phase
coal	Sedimentary rock composed of the compacted, lithified and altered remains of plants
wilting point	The point at which the rate of water leaving a plant's leaves is greater than the water uptake by the roots
surface	2.
latent heat of condensation	The amount of heat energy release to the environment when a gas changes its state to a liquid
water budget	See hydrologic accounting.
net solar radiation	The difference between the solar radiation directed downward and upward; net flux of solar radiation.
evapotranspiration	Combination of evaporation from free water surfaces and transpiration of water from plant surfaces to the atmosphere.
phylogenic classification	Classification of organisms based on genetic connections between other species.
glacial drift	A generic term applied to all glacial and glaciofluvial deposits.
rock flour	Very finely ground rock fragments that form between the base of a glacier and the underlying bedrock surface.
sea arch	A coastal landform composed of rock that resembles an arch
earthlight	The faint illumination of the dark part of the moon's disk produced by sunlight reflected onto the moon from the earth's surface and atmosphere.
thermodynamic laws	Laws that describe the physical processes, relationships, and phenomena associated with heat.
interflow runoff	The parts of runoff, caused by precipitation and/or snowmelt, that enters the ground and moves in upper levels of the soil mantle above the water table, heading towards the streams.
specific humidity	Relative humidity.Absolute zero ...
muscovite	Rock forming mineral of the mica group.
chemosphere	A vaguely defined region of the upper atmosphere in which photochemical reactions take place
radio atmometer	An instrument designed to measure the effect of sunlight on evaporation from plant foliage
carbon dioxide	A minor but very important component of the atmosphere, carbon dioxide traps infrared radiation