A vector term which includes both wind speed and wind direction.

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.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

Nested Grid Model generated every 12 hours by NCEP.

The gravity flow of water within soil.

The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

Conditions to which a device is subjected, not including the variable measured by the device. See normal operating conditions, reference operating conditions.

An old nautical term for mercury barometer.

A white disk 12" or more in diameter which is lowered into the sea to estimate transparency of the water. The depths are noted at which it first disappears when lowered and reappears when raised.

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

Difference between the temperatures of the dry-bulb and the wet-bulb thermometers of a psychrometer.

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

A wave resulting from the action of wind on a water surface.

The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air. Obtained by evaporation of water (or ice) from the muslin wick. Used in computing dew point and relative humidity.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.