An old nautical term for mercury barometer.

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

A general name for instruments which detect the presence of (but do not necessarily measure) small electrical charges by electrostatic means. Compare to electrometer.

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

The total area drained by a river and its tributaries. Same as river basin.

See evaporative opportunity.

A vector term which includes both wind speed and wind direction.

The range of operating conditions within which a device is designed to operate and for which operating influences are stated. See operating conditions, reference operating conditions.

A photometer that measures the received intensity of a distance tight source.

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.

A scale with the ice point at zero degrees and the boiling point of water at 80 degrees, with pressure of one atmosphere.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

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.

The gravity flow of water within soil.

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

Difference between the temperatures of the dry-bulb and the wet-bulb thermometers of a psychrometer.

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

A wind blowing in a direction perpendicular to the course of a moving object.