An instrument designed to measure quantities of heat. Sometimes used in meteorology to measure solar radiation.

See gain.

Contraction for radiosonde observation.

Same as photometer.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the mass of dry air. For many purposes, the mixing ratio may be approximated by the specific humidity.

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.

A device which surrounds a rain gauge and acts to maintain horizontal flow in the vicinity of the funnel so that the catch will not be influenced by eddies generated near the gauge. See Alter shield, Nipher shield, Wild fence.

An instrument which determines the altitude of an object with respect to a fixed level. There are two general types of altimeters: (a) the pressure altimeter, which gives an approximate measure of altitude from a pressure measurement and an assumed standa ...

A very sensitive electrostatic electrometer for measuring small potential differences.

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

Growth of a cloud or precipitation particle by the collision and union of a frozen particle with a super-cooled water drop.

A device which converts energy from one form into another, i.e. an ac generator transducer which converts the mechanical motion of anemometer cups into an electrical signal.

An anemometer which derives wind speed from measurements of dynamic wind pressures. Wind blowing into a tube develops a pressure greater than the static pressure, while wind blowing across a tube develops a pressure less than the static. This pressure dif ...

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

The range of operating conditions of a device within which operating influences are negligible. The range is usually narrow. Reference operating conditions are the conditions under which reference performance is stated and the base from which the values o ...

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

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

Same as dropsonde.

The intensity (flux per unit solid angle) of visible radiation weighted to take into account the variable response of the human eye as a function of the wavelength of light. Usually expressed in candles.