A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

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

An apparatus, used in studying soil temperatures, for measuring the total supply of heat during a given period.

Same as luminous intensity.

A conductor or system of conductors for radiating and/or receiving radio energy. Also called aerial.

See hurricane beacon.

A form of data transmission in which the bits of each character are all sent simultaneously, resulting in extremely fast communication but requiring a communication path for each bit. Compare to serial data transmission.

General name for an instrument which measures the evaporation rate of water into the atmosphere. See clay atmometer, evaporation pan, evapotranspirometer, Livingston sphere, Piche evaporimeter, radio atmometer.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.

A recording anemometer.

A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

A hydrometeor consisting of a visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface.

Transmitted energy which is modulated in order to carry information. Usually, it is in the form of a radio- frequency sine wave, modulated either in amplitude or in frequency.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

A method of winds aloft observation accomplished by tracking a balloon-borne radar target or radiosonde with either radar or a radio theodolite.

Thermometer for measuring the temperature in the soil at different depths.

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

In aviation terminology, route or terminal weather conditions of sufficiently low visibility to require the operation of aircraft under instrument flight rules.

A measure of luminous flux remaining in a light beam after it has passed through a specified distance of the atmosphere.