A device for measuring the frequency of occurrence of atmospherics whose intensity is greater than a predetermined level.

The statement that the viscosity of air is independent of the density of air.

A thermometer with a muslin-covered bulb which is moistened. used to measure wet-bulb temperature.

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.

Conditions to which a device is subjected, not including the variable measured by the device. See normal operating conditions, reference operating conditions.

An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

The record of an aneroid barograph.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

In thermodynamics, the integrating factor of the differential equation referred to as the first law of thermodynamics, In statistical mechanics, a measure of translational molecular kinetic energy (with three degrees of freedom). In general, the degree of ...

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

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 ...

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

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

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

See feed.

In general, pertaining to or affording an overall view. In meteorology, this term has become somewhat specialized in referring to the use of meteorological data obtained simultaneously over a wide area for the purpose of obtaining a comprehensive and near ...

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

Solar radiation scattered by particles in the atmosphere.

An old nautical term for mercury barometer.