A common unit used in measurement of atmospheric pressure. Defined as that pressure exerted by a one-inch column of mercury at standard gravity and a temperature of 0'C.

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

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

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

The correctable part of the inaccuracy of an instrument.

A refraction phenomenon similar to a parahelion, but occurring generally at a distance of 120

See radar theodolite, radio direction-finder.

Upwarddirected solar radiation, reflected by the earth's surface and the atmosphere.

Generic term for rapid variations in apparent position, brightness, or color of a distant luminous. object viewed through the atmosphere.

Not a linear function of the relevant variables.

Sir Napier Shaw's name for the approximate absolute temperature scale,

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

Occupational Safety and Health Administration. A regulatory office of the U.S. Department of Labor.

A liquid-in-glass or liquid-in-metal thermometer using mercury as the liquid.

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 ...

An instrument used for the determination of the electrical conductivity of the atmosphere.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

See standard atmosphere.

The state of the atmosphere, mainly with respect to its effects upon life and human activities. As distinguished from climate, weather consists of the short-term (minutes to months) variations of the atmosphere.

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