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.

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.

Same as marine rainbow.

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

The pressure unit of the meter-ton-second system of physical units. equal to 10 millibars or 101 dynes per cm2.

Same as mirror nephoscope.

Instrument for measuring the depth of water from precipitation that is assumed to be distributed over a horizontal, impervious surface and not subject to evaporation.

A liquid-in-glass thermometer which uses an organic substance such as alcohol as the thermometer liquid. This type of thermometer has a low freezing point and a high coefficient of expansion. It is less accurate, however, than a mercury thermometer.

An instrument which automatically determines the size distribution of raindrops.

Readily taking up and retaining moisture.

An instrument which determines the black-body temperature of a substance by measuring its thermal radiation.

A recording magnetometer.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

Same as recording rain gauge.

See bimetallic thermometer.

The combined processes by which water is transferred from the earth's surface to the atmosphere: evaporation of liquid or solid water plus transpiration from plants.

The water portion of the earth as distinguished from the solid part, called the lithosphere, and from the gaseous outer envelope, called the atmosphere.

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

Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.