The quantity to be measured (or modulated, or detected, or operated upon) which is received by an instrument. Thus, for a thermometer. temperature is the input quantity.

An instrument whose calibration is determined by comparison with an absolute instrument.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

(1) The ratio of the speeds of a chemical reaction at two temperatures differing by 10

The difference between the outgoing infrared terrestrial radiation of the earth's surface and the downcoming infrared counterradiation from the atmosphere.

For a given location, a measure of the long-range effectiveness of precipitation in promoting plant growth. Also called precipitation-evaporation index.

(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 ...

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

A type of directional antenna used on some types of radar and radio equipment consisting of an array of elemental, single- wire dipole antennas and reflectors.

pattern barometer-Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

An up slope wind due to local surface heating. Opposite of katabatic wind.

The value of atmospheric pressure to which the scale of a pressure altimeter is set so as to indicate airport elevation. The altimeter setting is included as part of an aviation weather observation.

The total infrared radiation emitted from the earth's surface. To be carefully distinguished from atmospheric radiation, effective terrestrial radiation, and insolation.

A psychrometer in which the ventilation is provided by a suction fan.

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

A point (or line) on a scale used for reference or comparison purposes. In calibration of meteorological thermometers, for example, the fiducial points are 100

A radar term for a single pulse of radio energy.

An absolute pyhrliometer, developed by C.G. Abbott, in which the radiation-sensing element is a blackened water-calorimeter.

The process by which events in the real world are translated into machine-readable signals.