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.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

Same as precipitation-evaporation ratio.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

Same as contact anemometer.

The sum of solar and terrestrial radiation.

An instrument which determines the altitude of an object with respect to a fixed level. There are two general types of altimeters: (a) the pressure altimeter, which gives an approximate measure of altitude from a pressure measurement and an assumed standa ...

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. Usually expressed in candles.

Liquid water at temperatures colder than freezing.

A form of data transmission in which the bits of each character are sent one at a time along a single communication path. Compare to parallel data transmission.

See aneroid capsule.

A modification of the dew cell used in radiosonde equipment.

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

The general term for dry atmospheric suspensoids, including dust, haze, smoke. and sand. Compare to hydrometeor.

A small, limited-capacity central processing unit contained entirely on one semiconductor chip.

An instrument which measures the scattering function of particles suspended in a medium in order to determine the visual range through the medium. See visibility meter.

The difference between the solar radiation directed downward and upward; net flux of solar radiation.

That part of an audio-modulated radiosonde consisting of the baroswitch, the sensing elements, the reference elements, and the relay.