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.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

Wind with a speed between 22 and 27 knots (25 and 31 mph); Beaufort scale number 6.

A measure of the amount of "spin" (or rotation) in the atmosphere.

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

The range through which the input may be varied without initiating a response. Usually expressed as a percentage of full-scale range.

An elongated area of relatively low atmospheric pressure. Usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow. The opposite of a ridge.

The state of the atmosphere, mainly with respect to its effects upon life and human activities. As distinguished from climate, weather consists of the short-term (minutes to months) variations of the atmosphere.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

A standard interface between a computer input/output port and a peripheral device. Signal properties including time duration, voltage. and current, are specified by the Electronic Industries Association.

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.

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

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.

Same as rain-intensity gauge.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

The greatest distance at which it is just possible to see and recognize with the unaided eye (1) in the daytime, a prominent dark object against the sky at the horizon, and (2) at night, a known, preferably unfocused, moderately intense light source.

The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

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

A unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.