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

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

The distance or length of flow of the air past a point during a given interval of time.

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

Precipitation caused by the ascent of moist air over an orographic barrier such as a Mountain range.

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.

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

An instrument that shows changes in humidity.

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 array of indicating marks and figure in relation to which the position of an index is observed, i.e. a scale plate on a recorder.

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.

Same as marine rainbow.

The upper surface of a column of liquid.

See standard atmosphere.

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.

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.

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.

The water volume within a specified portion of a stream channel.

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