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 ...

Abbreviation for precipitation-evaporation ratio.

Name sometimes given to a transmissometer.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

Same as wind sock.

A line drawn through points of equal humidity on given surface.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

Apparatus designed to measure and record the size distribution of raindrops as they occur in the atmosphere.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

A large plastic constant-level balloon for duration flying (in excess of 24 hours) at altitudes above 40,000 feet, used for the determination of wind fields and the measurement of upper atmospheric parameters.

See Koschmieder's law.

Clouds which cover between 6/10 and 9/10 of the sky. See Sky Terminology.

Same as windsock.

That portion of the atmosphere which is above the lower troposphere. Generally applied to levels above 850 mb.

Pertaining to rain, or more broadly, to precipitation.

(1) The ratio of the speeds of a chemical reaction at two temperatures differing by 10

Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.