The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

Lowest altitude in the atmosphere over a given location at which the air temperature is 0

The physical exposure of an instrument. The effect of immediate environment upon the representativeness of the measurements obtained by meteorological instruments is considerable and not always correctable. The purpose of the instrument shelter is to prov ...

Same as parhelion.

A method of winds aloft observation in which the elevation and azimuth angles of a theodolite are read while visually tracking a pilot balloon. Balloon height data is estimated from assumed balloon ascension rates.

Precipitation composed of white or translucent ice crystals, chiefly in complex branched hexagonal forms.

A thermometer based upon the principle that the velocity of a sound wave is a function of the temperature of the medium through which it passes. Sonic thermometers possess very short time-constants and eliminate radiation error.

In aviation terminology, route or terminal weather conditions of sufficiently low visibility to require the operation of aircraft under instrument flight rules.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

Any conventional barometer fitted with an extended scale so that atmospheric pressure measurements may be made at both high and low altitudes.

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 ...

Of equal or constant pressure, with respect to either space or time.

A pressure tube anemometer, consisting of a pitot tube mounted on the windward end of a wind vane and a suitable manometer to measure the developed pressure and calibrated in units of wind.

Solar radiation of selected wavelengths.

An instrument which automatically records the measurement of two or more meteorological elements.

Pertaining to rain, or more broadly, to precipitation.

The mean difference between the readings of a given instrument and those of a standard instrument.

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

Graduated fixed stake used in regions of abundant snowfall to facilitate the measurement of snow depth.

Same as water year.