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. Usually expressed in percent.

See sea-water thermometer, reversing thermometer.

Name sometimes given to a transmissometer.

See hook gauge.

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. The modified characteristic may be frequency, phase, and/or a ...

A large body of air having similar horizontal temperature and moisture characteristics.

A radar term for a single pulse of radio energy.

American Standard Code for Information Interchange. A standard code used to represent data using 8 bits (7 data bits and I parity bit) per character.

A type of wind vane having a split or V-shaped tail. The apex orients itself to the direction of the wind.

Hygrometer in which the dew (frost) point is determined by observing the temperature of an artificially cooled surface at the moment at which dew (frost) first appears on it.

Same as constant-level balloon.

A feeble oscillatory disturbance of the earth's crust, detectable only by very sensitive seismographs. Certain types of microseisms seem to be closely correlated with pressure disturbances. See microbarm.

An instrument for measuring the pressure of the atmosphere. The two principle types are aneroid and mercurial.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

An instrument for measuring the difference between incoming and outgoing terrestrial radiation.

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

A scale with the ice point at zero degrees and the boiling point of water at 80 degrees, with pressure of one atmosphere.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

An instrument used for the determination of the electrical conductivity of the atmosphere.