A constant which describes the performance of a wind vane in response to a step change in wind direction. It is calculated from the relative amount of overshoot on two successive swings (half cycles) of a decaying oscillation. This specification is dimens ...

A description or explanation of the manner in which the height of the ceiling is determined, i.e. aircraft ceiling, balloon ceiling. estimated ceiling, indefinite ceiling, measured ceiling, precipitation ceiling.

See bimetallic thermometer.

The component of the radiosonde which includes the modulating blocking oscillator and the radiofrequency carrier oscillator.

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

An atmospheric phenomenon, other than clouds, which obscures a portion of the sky from the point of observation. Also called obscuration.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

See calorie.

A refraction phenomenon similar to a parahelion, but occurring generally at a distance of 120

A momentary decrease in the speed of the wind.

An instrument used to indicate wind direction.

Literally "not wet", containing no liquid.

A device, similar to a phytometer, for measuring transpiration. It consists of a small vessel containing water and sealed so that the only escape of moisture is by transpiration from a leaf, twig, or small plant with its cut end inserted in the water.

Force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

National Weather Service. Administered by the U.S. Department of Commerce.

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

See photometer.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

Particle on which the freezing of water occurs.

A system in which radar techniques are used to determine the range, elevation, and azimuth of a radar target carried a!oft by a radiosonde, so that wind data may be obtained along with the other meteorological data.