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 portion of the strearnflow during any month or year derived from precipitation in previous months or years.

variable audio-modulated radiosonde developed at the Bureau of Standards and used by the United States weather services.

Same as contact anemometer.

An instrument for measuring the intensity of direct solar radiation at normal incidence. See Angstrom compensation pyrheliometer, Eppley pyrheliometer, Michaelson actinograph. silver- disc pyrheliometer, spectropyrheliometer, waterflow pyrheliometer.

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 ...

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

The rising of cold water from the deeper areas of the ocean to the surface. This phenomena often occurs along the California coast during the spring and summer.

See ceilometer.

A method of winds aloft observation accomplished by tracking a balloon-borne radar target or radiosonde with either radar or a radio theodolite.

The degree of conformity of an indicated value to an accepted standard value, or ideal value. See accuracy rating, measured accuracy.

Abbreviation for precipitation-evaporation ratio.

Conditions to which a device is subjected, not including the variable measured by the device. See normal operating conditions, reference operating conditions.

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

A recording anemometer.

A recording siphon barometer.

Automated Weather Observing Station. A self-contained weather station designed to make aviation weather observations without operator involvement.

A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.

The direction toward which the wind is blowing; with the wind.

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.