The number of cycles per second between the limits of a frequency band.

Pertaining to the action or effect of the wind. Derived from the name of the Greek god of the winds, Aeolus.

A generic term for any machine that enables a human being to communicate with a computer.

A thermometer used in aircraft which automatically corrects for adiabatic and frictional temperature rises by imparting a rotary motion to the air passing the thermal sensing element.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

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

See Koschmieder's law.

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

A captive balloon used to maintain meteorological equipment aloft at approximately a constant height. The kytoon is streamlined and combines the aerodynamic properties of a balloon and a kite.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

Same as windsock.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.

General term for an instrument used to make direct measurements of visual range or measurements of the physical characteristics of the atmosphere which determine the visible range.

An ice coating with a consistency intermediate between glaze and rime.

A thermodynamic change of state in a system in which there is no transfer of heat or mass across the boundaries of the system. In an adiabatic process, compression always results in warming, expansion in cooling. Compare to diabatic process.

Downward-facing pyranometer used for measuring reflected solar radiation.

An instrument for measuring the frost point of the atmosphere.

Same as Aeolian.

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