A measure of the intensity of gusts given by the ratio of the total range of wind speed between gusts and the intermediate periods of lighter wind to the mean wind speed, averaged over both gusts and lulls.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...

See stage.

A very sensitive electrostatic electrometer for measuring small potential differences.

The record made by a hygrograph.

A local variation in the wind direction or speed. This condition can present danger to aircraft, especially at landing, when a sudden shift from headwind to tailwind can cause a rapid loss of airspeed and lift.

Reduction of visibility by strong winds blowing across dry ground with little or no vegetation. Visibilities of 1/8 mile or less over a widespread area are criteria for a Blowing Dust Advisory.

An instrument resulting from the combination of a thermograph and a hygrograph and furnishing, on the same chart, simultaneous time recording of ambient temperature and humidity.

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

Same as rain-intensity gauge.

Same as atmospheric pressure.

Either of two colored luminous spots that appear at points 22

A type of cooling-power anemometer based upon the principle that the time constant of a thermometer is a function of its ventilation.

Electromagnetic radiation of very short wavelength. lying within the wavelength interval of 0.1 to 1.5 angstroms (between gamma rays and ultraviolet radiation). X-rays penetrate various thicknesses of all solids, and they act on photographic plates in the ...

The maximum positive and negative deviation observed in testing a device under specified conditions and by a specified procedure. It is usually measured as an inaccuracy and expressed as accuracy, typically in terms of the measured variable, percent of sp ...

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

A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

A clock-driven instrument mounting which automatically and continuously points in the direction of the sun. It is used with a pyrheliometera,hen continuous direct solar radiation measurements are required.

modulated radiosonde-A radiosonde which transmits the indications of the meteorological sensing elements in the form of pulses spaced in time. The meteorological data are evaluated from the intervals between the pulses. Also called timeinterval radiosonde ...