The algebraic difference between the upper and lower limits of the measuring range of an instrument, i.e. a thermometer with a range of -35 to 50

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.

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

An instrument which automatically records the measurement of two or more meteorological elements.

The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.

A relatively small-scale, downward moving current of air.

A thermometer which utilizes the thermal properties of gas. There are two forms of this instrument: (a) a type in which the gas is kept at constant volume, and pressure is the thermometric property, and (b) a type in which the gas is kept at constant pres ...

Eluding precise prediction, completely irregular.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

Automated Weather Observing Station. A self-contained weather station designed to make aviation weather observations without operator involvement.

See calorie.

See hurricane beacon.

An instrument of the aspiration condenser type which measures the concentration and mobility of small ions.

Nested Grid Model generated every 12 hours by NCEP.

Of or pertaining to the air, atmosphere, or aviation. Also, same as antenna.

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

The most common of the principal rainbow phenomena, which appears as an arc of about 42

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.

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