Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.

An instrument used to indicate wind direction.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

Interational thermometric scale on which the freezing point of water equals 0

General term for an instrument which records the vertical electric current in the atmosphere.

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

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

Same as contact anemometer.

The difference between temperature measurements taken at two significant levels above the ground. Temperatures at 10 and 40 meters are commonly used.

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.

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

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.

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

A general term for instruments designed to measure the amount of cloudiness.

See evaporation pan.

Same as mirror nephoscope.

The ratio of the amount of electromagnetic radiation reflected by a body to the amount incipient upon it, commonly expressed as a percentage. The albedo is to be distinguished from the reflectivity, which refers to one specific wavelength.

Same as wind sock.

National Weather Service. Administered by the U.S. Department of Commerce.