Either of two colored luminous spots that appear at points 22

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

The correctable part of the inaccuracy of an instrument.

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

A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

Anemometer which measures wind speed by measuring the degree of cooling of a metal film heated by an electric current. A type of cooling-power anemometer.

A standard interface between a computer input/output port and a peripheral device. Signal properties including time duration, voltage. and current, are specified by the Electronic Industries Association.

An instrument of the aspiration condenser type which measures the concentration and mobility of small ions.

A type of electrical thermometer in which the thermal element is a substance whose electrical resistance varies with the temperature. Such thermometers can be made with very short time constants and are capable of highly accurate measurements.

Same as atmometer.

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 used to measure and record earthquake vibrations and other earth tremors.

See Koschmieder's law.

In a radiosonde observation, a level (other than a standard level) for which values of pressure, temperature, and humidity are reported because temperature and/or humidity data at that level is sufficiently important or unusual to warrant the attention of ...

The record of a barograph.

The direction, with respect to true north, from which the wind is blowing. Distinguish from magnetic wind direction. In all standard upper-air and surface weather observations, it is true wind direction that is reported.

Automated Weather Observing Station. A self-contained weather station designed to make aviation weather observations without operator involvement.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

To free something from the binding action of ice by warming it to a temperature above the melting point of ice. Also, a warm spell when ice and snow melt.