The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

A curve showing the variation of temperature with height in the free air. See lapse rate.

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

An instrument for measuring differences of electric potential.

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

The attenuation of light.

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

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

The upper surface of a column of liquid.

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

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.

See radar theodolite, radio direction-finder.

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

Nested Grid Model generated every 12 hours by NCEP.

The stage on a fixed river gauge at which it is necessary to begin issuing warnings or river forecasts if adequate precautionary measures are to be taken before flood stage is reached.

A cup anemometer with its shaft mechanically coupled to a magneto.

The correctable part of the inaccuracy of an instrument.

Routine broadcast of meteorological information for aircraft in flight.

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

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.