See gust and peak gust.

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 ...

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

A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

See sea-water thermometer, reversing thermometer.

See wind vane.

A buoyant balloon rising freely in the atmosphere, as opposed to a captive balloon.

Programmable Read-Only Memory. Read-only memory which can be programmed by the user using a special hardware programmer.

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.

An instrument designed to measure the effect of sunlight on evaporation from plant foliage. It consists of a porous clay atmometer whose surface has been blackened so that it absorbs radiant energy.

Apparatus consisting of (a) standard radiosonde and radiosonde ground equipment to obtain upper-air data on pressure, temperature, and humidity, and (b) a self-tracking radio direction-finder to provide the elevation and azimuth angles of the radiosonde s ...

Instrument for measuring the mean intensity of glo global solar radiation (direct and diffuse) near the earth's surface in a specified time interval.

A thermograph in which ventilation is provided by a suction fan.

Any emission of light at temperatures below that required for incandescence.

A special type of radar target, usually a comer reflector, tied beneath a free balloon and designed to be an efficient reflector of radio energy.

An instrument used to measure the amount of dew formed on a given surface.

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

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

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.