A local variation in the wind direction or speed. This condition can present danger to aircraft, especially at landing, when a sudden shift from headwind to tailwind can cause a rapid loss of airspeed and lift.

Same as atmometer.

Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day.

Video Display Terminal. An input and display device which includes a keyboard and a screen and allows a human to communicate with a computer.

Same as mercury barometer.

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

A medium-sized instrument shelter. It is a white louvered box with a flat double to of and is mounted four feet above the ground on a four-legged stand.

Emission or transfer of energy in the form of electromagnetic waves or particles.

A recording anemometer.

A special type of radar target, usually a comer reflector, tied beneath a free balloon and designed to be an efficient reflector of radio energy.

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.

See constant-level balloon.

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

A method of winds aloft observation essentially the same as a pilot balloon observation except the height data is derived from the radiosonde observation rather than from assumed ascension rates.

The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

Same as atmospheric pressure.

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.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

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

Any quantity, such as force velocity, or acceleration, which has both magnitude and direction at each point in space, as opposed to scalar which has magnitude only. Such a quantity may be represented geometrically by an arrow of length proportional to its ...