The distance or length of flow of the air past a point during a given interval of time.

Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day.

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

A type of directional antenna used on some types of radar and radio equipment consisting of an array of elemental, single- wire dipole antennas and reflectors.

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

A hygrometer in which the rotation of the hygrometric element is a function of humidity.

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

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

An aviation weather forecast for a specific flight.

The center of an area of high pressure, usually accompanied by anticyclonic and outward wind flow. Also known as an anticyclone.

A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

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 graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

A self-recording thermometer.

Instrument which measures and records the amount of evaporation over time.

Pertaining to rain, or more broadly, to precipitation.

The process by which events in the real world are translated into machine-readable signals.

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

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

Video Display Terminal. An input and display device which includes a keyboard and a screen and allows a human to communicate with a computer.