The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

A type of atmometer. It is a pan used in the measurement of the evaporation of water into the atmosphere. The NWS Class A pan is a cylindrical container 48 inches in diameter and 10 inches deep.

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.

A measure of the degree to which the weather or climate of a region is favorable to the process of evaporation. Usually considered to be the rate of evaporation. under existing atmospheric conditions, from a surface of water which is chemically pure and h ...

Same as atmometer.

Instrument which measures and records the amount of evaporation over time.

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.

An instrument which measures the rate of evapotranspiration. It consists of a vegetation soil tank so designed that all water added to the tank and all water left after evapotranspiration can be measured.

The attenuation of light.

The transducer's output when the maximum sensed value is applied to the transducer's input. For example, the F.S. output of a 4-20 mA transmitter is 20 mA, whereas its span is only 16mA.

Federal Aviation Administration.

A temperature scale on which the freezing point of water equals 32

The source of illumination for an antenna reflector. Also called antenna feed.

A point (or line) on a scale used for reference or comparison purposes. In calibration of meteorological thermometers, for example, the fiducial points are 100

That temperature at which, in a specified latitude, the reading of a particular barometer requires no temperature or latitude correction.

The officially designated elevation of an airport above mean sea level, taken as the highest point on any of the runways of the airport. Same as airport elevation.

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

Programs or instructions which are stored in readonly memory.