A wind (or component thereof) directed down the slope of an incline and caused by greater air density near the slope than at the same levels some distance horizontally from the slope. Also called drainage wind and sometimes called katabatic wind.

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...

In meteorology, a deflecting force acting on a body in motion and resulting from the earth's rotation. It deflects air currents to the right in the northern hemisphere and to the left in the southern hemisphere, thus having an effect on wind direction.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

A thermopile used in some types of radiation instruments. See solarimeter.

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

Balance of the water resources of a region, comparing precipitation and inflow with outflow, evaporation, and accumulation.

The process by which water in plants is transferred as water vapor to the atmosphere. Also, the amount of water so transferred.

An instrument for determining the degree of polarization of light. See photopolarimeter.

Determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.

Anemometer whicb measures wind speed by measuring the degree of cooling of a metal wire heated by an electric current. A type of cooling power anemometer.

The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface. This result of infrared (long-wave) absorption and reemission by the atmosphere is the principal factor in the greenhouse effect.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

The rate of decrease of pressure per unit distance at a fixed time.

A self-recording thermometer.

Complementary Metal-Oxide Semiconductor. A method of making silicon chips that results in low power consumption by the circuits.

An instrument, for the recording of two or more meteorological parameters, in which the ventilation is provided by a suction fan.

A type of pressure-tube anemometer, named after the inventor.

A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time. A U-tube min/max thermometer