Anemometer which generates an electrical contact output with a frequency proportional to wind speed.

A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

Same as marine rainbow.

Transmitted energy which is modulated in order to carry information. Usually, it is in the form of a radio- frequency sine wave, modulated either in amplitude or in frequency.

The programs and instructions which direct a computer.

See photometer.

The source of illumination for an antenna reflector. Also called antenna feed.

A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

A captive balloon used to maintain meteorological equipment aloft at approximately a constant height. The kytoon is streamlined and combines the aerodynamic properties of a balloon and a kite.

A general term for instruments designed to measure the speed or force of the wind.

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

A line of equal or constant pressure.

The cardinal points of the compass, i.e. north, south, east, west.

A wind vane used to obtain the horizontal and vertical components of the wind.

A wind scale adapted by the U.S. Forest Service for use in the forested areas of the northern Rocky Mountains (NRM). It is an adaptation of the Beaufort wind scale. The difference between these two scales lies in the specification of the visual effects of ...

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

Instrument for measuring the depth to which the soil is frozen.

A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

An instrument for measuring the difference between incoming and outgoing terrestrial radiation.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.