An instrument developed by K. Angstrom for measuring the effective terrestrial radiation. It consists of four manganin strips, of which two are blackened and two are polished. The blackened strips are allowed to radiate to the atmosphere while the polishe ...

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.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

An instrument of the aspiration condenser type which measures the concentration and mobility of small ions.

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

Abbreviation for precipitation-evaporation quotient.

Complementary Metal-Oxide Semiconductor. A method of making silicon chips that results in low power consumption by the circuits.

Lacking a relationship to a time base or clock. In asynchronous communications, individual data characters are sent at an arbitrary rate.

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.

The true freezing point of water. The temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere.

A measure of the intrinsic luminous intensity emitted by a source in a given direction. Luminance is a measure only of light. The comparable term for electromagnetic radiation in general is radiance.

The distance or length of flow of the air past a point during a given interval of time.

A general term for instruments designed to measure the amount of cloudiness.

Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.

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

A recording hair hygrometer.

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

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

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

The limiting values of ceiling, visibility, and wind, or runway visual range, established as safety minimum for aircraft landings and take-offs.