(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 ...

See hydrologic accounting.

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

See calorie.

A white disk 12" or more in diameter which is lowered into the sea to estimate transparency of the water. The depths are noted at which it first disappears when lowered and reappears when raised.

A hypothetical, ideal body which absorbs completely all incident radiation. independent of wavelength and direction. No actual substance behaves as a true black body, although platinum black and other soots rather closely approximate this ideal. However, ...

Air in motion relative to the surface of the earth. Almost exclusively used to denote the horizontal component.

A rotation anemometer in which the axis of rotation is horizontal. The instrument has either flat vanes (as in the air meter) or helicoidal vanes (as in the propeller anemometer). The relation between wind speed and angular rotation is almost linear.

In folklore, a name for wind.

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

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

The difference between temperature measurements taken at two significant levels above the ground. Temperatures at 10 and 40 meters are commonly used.

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

An old nautical term for mercury barometer.

An instrument for measuring the pressure of gases and vapors. A mercury barometer is a type of manometer.