Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

Same as humidity strip.

A self-recording psychrometer.

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

The maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.

An instrument for studying, or examining substances in, polarized light. See Savant polariscope.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

Solar radiation of selected wavelengths.

An instrument for measuring the ultraviolet in solar and sky radiation.

An up slope wind due to local surface heating. Opposite of katabatic wind.

Meteorological information issued by a watch office concerning the occurrence or forecast of weather phenomena which may affect the safety of aircraft operations.

The energy of any type of electromagnetic radiation. Also called radiation.

The officially designated elevation of an airport above mean sea level, taken as the highest point on any of the runways of the airport. Same as airport elevation.

Same as Aeolian.

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

Same as recording rain gauge.

A method of winds aloft observation essentially the same as a pilot balloon observation except the height data is derived from the radiosonde observation rather than from assumed ascension rates.

A small anemometer with flat vanes which indicates the number of linear feet or meters of air which have passed the instrument during its exposure.

Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed.

The amount of moisture which, if available, would be removed from a given land area by evapotranspiration. Expressed in units of water depth.