Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

A radiosonde whose carrier wave is switched on and off in such a manner that the interval of time between the transmission of signals if a function of the magnitude of the meteorological elements being measured.

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 ...

A generic term for any machine that enables a human being to communicate with a computer.

A line of equal or constant temperature.

See calorie.

A balloon used to carry a radiosonde aloft, considerably larger than pilot balloons or ceiling balloons.

A measure of the attenuation due to scattering, of light as it traverses a medium containing scattering particles.

Any device or instrument for measuring salinity, especially one based on electrical conductivity methods.

An instrument used to measure the water vapor content of the air. A type of hygrometer. It consists of a wet-bulb and a dry-bulb thermometer. See aspiration psychrometer, Assmann psychrometer. hygrodeik, sling psychrometer.

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

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 ...

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

In radiometry, a measure of the intrinsic radiant intensity emitted by a radiator in a given direction.

An instrument for measuring the frost point of the atmosphere.

A cone-tipped metal rod designed to be driven downward into deposited snow or firn. The measured amount of force required to drive the rod a given distance is an indication of the physical properties of the snow or firn.

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

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

Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e. cubic feet per second.

A temperature scale with the ice point at 273 degrees and boiling point of water at 373 degrees. It is intended to approximate the Kelvin temperature scale with sufficient accuracy for many sciences, notably meteorology.