Temperature based on an absolute scale.

A measure of the intensity of gusts given by the ratio of the total range of wind speed between gusts and the intermediate periods of lighter wind to the mean wind speed, averaged over both gusts and lulls.

Any source of radiant energy, especially electromagnetic energy.

An evaluation, according to set procedures, of those weather elements which are most important for aircraft operations. Always includes cloud height or vertical visibility, sky cover, visibility, obstructions to vision, certain atmospheric phenomena, and ...

Same as freezing point.

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 evaluation of upper air temperature, pressure, and humidity from radio signals received from a balloon- borne radiosonde.

An instrument used for measuring geometric angles. See radio direction-finder.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

An instrument which measures the spectral distribution of the intensity of direct solar radiation.

The general term for anemometers operating on the principle that the heat transfer to air from an object at an elevated temperature is a function of the air speed. Examples are the hot-wire anemometer and the katathermometer.

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

A particular pattern of snow sampler having an internal diameter of 1.485 inches so that each inch of water in the sample weighs one ounce.

Any sudden and heavy rain, almost always of the shower type.

A wind blowing in a direction perpendicular to the course of a moving object.

(1) The initial component or the sensing element of a measuring system. For example, the receiver of a rain gauge is the funnel which captures the rain and the receiver of a thermoelectric thermometer is the measuring thermocouple. (2) An instrument used ...

The height of the cloud base above the local terrain.

Readily taking up and retaining moisture.

The number of cycles per second between the limits of a frequency band.

A radar which is used to obtain the azimuth elevation, and slant range of an airborne target.