A hydrometeor consisting of an aggregate of microscopic and more-or-less hygroscopic water droplets suspended in the atmosphere. It reduces visibility to a lesser extent than fog. The relative humidity of mist is often less than 95 percent.

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

Physical equipment used in data processing. Compare to firmware, software.

Meteorological information issued by a watch office concerning the occurrence or forecast of weather phenomena which may affect the safety of aircraft operations.

Same as atmometer.

The portion of the strearnflow during any month or year derived from precipitation in previous months or years.

Wind with a speed between 28 and 33 knots (32 and 38 mph); Beaufort scale number 7.

A radar term for a single pulse of radio energy.

A thin metal disc partially evacuated of air used to measure atmospheric pressure by measuring its expansion and contraction.

In Jeffreys' classification, a wind for which the pressure force exactly balances the viscous force, in which the vertical transfers of momentum predominate.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

The stage on a fixed river gauge at which it is necessary to begin issuing warnings or river forecasts if adequate precautionary measures are to be taken before flood stage is reached.

A forecast of weather elements of particular interest to aviation; including ceiling, visibility, upper winds, icing, turbulence, precipitation types, and storms.

A device that combines several separate communications signals into one and outputs them on a single line.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

Operation mode of a communication circuit in which each end can simultaneously transmit and receive.

An early and once universal name for the mercury barometer.

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.

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