Forecasting weather by the use of numerical models, run on high speed computers. Most of the NWP for the National Weather Service is done at the National Centers for Environmental Prediction (NCEP).

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

Any conventional barometer fitted with an extended scale so that atmospheric pressure measurements may be made at both high and low altitudes.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

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

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...

Navy Operational Global Atmospheric Prediction System. A global meteorological model operated by the Department of Defense.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

Quantitative Precipitation Forecast.

A mercury barometer which measures atmospheric pressure by weighing the mercury in the column or cistern.

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

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 process by which one object becomes adhered to another by the binding action of ice.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

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 that automatically records pressure and temperature.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

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

See radar theodolite, radio direction-finder.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.