A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

General term for any device that measures precipitation: principally a rain gauge or snow gauge.

A common type of liquid-inglass thermometer, used, in meteorology, in psychrometers and as a maximum thermometer.

Any meteorological instrument, such as a radiosonde, in which the recording apparatus is located at some distance from the measuring apparatus.

An instrument for determining the dust content of a sample of air. Also spelled conimeter.

The officially designated elevation of an airport above mean sea level, taken as the highest point on any of the runways of the airport. Same as airport elevation.

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 current meter consisting of six conical cups, mounted around a vertical axis, which rotate and generate a signal with each rotation. Tail vanes and a heavy weight stabilize the instrument.

The lowest value of a measured quality at which a sensor meets its accuracy specification.

The difference between the outgoing infrared terrestrial radiation of the earth's surface and the downcoming infrared counterradiation from the atmosphere.

A radiosonde which transmits the indication of the meteorological sensing elements in the form of a code consisting of combinations of dots and dashes.

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

The maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.

Wind with a speed between 48 and 55 knots (55 and 63 mph), Beaufort scale number 10.

A reflecting type telescope with a 45

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

The record made by a hygrograph.

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.

An instrument used for measuring the specific gravity of a liquid.

Same as water year.