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 ...

A radar term for a single pulse of radio energy.

The processing of the form or mode of a signal so as to make it intelligible to, or compatible with, a given device.

Same as mirror nephoscope.

A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. Compare to Pit ...

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

Either of two colored luminous spots that appear at points 22

Same as radiation pattern. Anticyclone-An area of high atmospheric pressure which has a closed circulation that is anticyclonic (clockwise in northern hemisphere and counterclockwise in southern hemisphere).

Clouds which cover between 6/10 and 9/10 of the sky. See Sky Terminology.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

The programs and instructions which direct a computer.

Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source. Direct solar radiation is measured by pyrheliometers.

An instrument used to measure the amount of dew formed on a given surface.

A systematic summary of the terms (inflow, outflow, and storage) of the storage equation as applied to the computation of soil-moisture changes, ground-water changes, etc. An evaluation of the hydrologic balance of an area. Also called basin accounting, w ...

Instrument for measuring the mean intensity of glo global solar radiation (direct and diffuse) near the earth's surface in a specified time interval.

Same as mercury barometer.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

Apparatus from which the nature and time of precipitation may be determined.

Formation of a single water drop by the union of two or more colliding drops.

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.