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.

A general term for instruments designed to measure the speed or force of the wind.

The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface. In terms of the hydrologic cycle, the ...

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

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 ...

In radiometry, a measure of the intrinsic radiant intensity emitted by a radiator in a given direction.

The temperature to which a sample of air must be cooled, while the mixing ratio and barometric pressure remain constant, in order to attain saturation by water vapor. When this temperature is below O

The record or trace made by a microbarograph.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

Pertaining to rain, or more broadly, to precipitation.

Integrated Flood Observing and Warning System. National Weather Service flood warning program.

In general, the transformation of data from a "raw" form to some useable form. In meteorology, this often refers to the conversion of the observed value of an element to the value which it would theoretically have at some selected or standard level. The m ...

An instrument whose calibration is determined by comparison with an absolute instrument.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

Any one of six gases, helium, neon, argon, krypton, xenon, and radon, all of whose shells of planetary electrons contain stable numbers of electrons such that the atoms are chemically inactive.

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

A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

A graphical device used for the determination of the speed of the geostrophic wind from the isobar or contour-line spacing on a synoptic chart.

A type of modulation in which the frequency of a continuous radio carrier wave is varied in accordance with the properties of a second (modulating) wave.