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

A point (or line) on a scale used for reference or comparison purposes. In calibration of meteorological thermometers, for example, the fiducial points are 100

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 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.

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves.

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

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.

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

See standard atmosphere.

An instrument that shows changes in humidity.

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 fogbow.

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

The upper surface of a column of liquid.

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

Same as marine rainbow.

Not a linear function of the relevant variables.

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.