As used by the U.S. Army Corps of Engineers, the departure (in

A thermometer whose sensitive element has been made to resemble a black body by covering it with lamp black. The thermometer is placed in an evacuated transparent chamber which is maintained at a constant temperature. The instrument responds to insolation ...

See ceilometer.

Eluding precise prediction, completely irregular.

A hygrometer which includes an arrangement for the time recording of atmospheric humidity.

film hygrometer element-An electrical hygrometer element constructed of a plastic strip coated with a film of carbon black dispersed in a hygroscopic binder. Variations in atmospheric moisture content vary the volume of the binder and thus change the resi ...

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

Name sometimes used in place of pyranometer as a generic term.

The transmission of data collected at a remote location over communications channels to a central station.

A thin metal disc partially evacuated of air used to measure atmospheric pressure by measuring its expansion and contraction.

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

Diffuse solar radiation which has the same intensity in all directions.

A type of cloud height indicator which uses a searchlight to project vertically a narrow beam of light onto the cloud base. The height of the cloud is determined using a clinometer, located at a known distance from the ceiling light, to measure the angle ...

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 unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.

The programs and instructions which direct a computer.

An instrument used for measuring the specific gravity of a liquid.

In nautical terminology, a contraction for "weather glass" (a mercury barometer).

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.