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

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 thermometer which uses a transducing element whose element proper-ties are a function of its thermal state. Common meteorological examples of such thermometers are the resistance thermometer and the thermoelectric thermometer.

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 ...

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.

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

An instrument used to reveal but not necessarily measure the presence of an electrical quantity. It is used to display the output of a sensing element after suitable amplification and modification. Sometimes called display.

See radar theodolite, radio direction-finder.

A device, similar to a potometer, for measuring transpiration, consisting of a vessel containing soil in which one or more plants are rooted and sealed so that water can escape only by transpiration from the plant.

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

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

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

An instrument for the measurement of the rate of ice accretion on an unheated body.

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

The upper surface of a column of liquid.

A wooden enclosure about sixteen feet square and eight feet high with a precipitation gauge at its center. The function of the fence is to minimize eddies around the gauge and thus insure a catch that is representative of the actual rainfall or snowfall.

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.

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

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

A coating of ice, generally clear and smooth. formed by the freezing of supercooled water on a surface.