The total of direct solar radiation and diffuse sky radiation received by a unit horizontal surface. Global radiation is measured by pyranometers.

Abbreviation for radio frequency.

The addition of one or more redundant bits to information to verify its accuracy.

The temperature to which a sample of air must be cooled, while the mixing ratio and barometric pressure remain constant, in order to attain saturation by water vapor. When this temperature is below O

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

(1) The initial component or the sensing element of a measuring system. For example, the receiver of a rain gauge is the funnel which captures the rain and the receiver of a thermoelectric thermometer is the measuring thermocouple. (2) An instrument used ...

Contraction for pilot balloon observation.

Same as luminous intensity.

Anemometer which measures wind speed by measuring the degree of cooling of a metal film heated by an electric current. A type of cooling-power anemometer.

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.

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

Same as wind sock.

A reversing thermometer (for seawater temperature) which is not protected against hydrostatic pressure. The mercury bulb is therefore squeezed, and the amount of mercury broken off on reversal is a function of both temperature and of hydrostatic pressure.

force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

An automatic, recording cloud height indicator.