Central Processing Unit. The part of a computer which controls and directs all functions.

A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

A recording anemometer.

The maximum distance along the runway at which the runway lights are visible to a pilot at touchdown. Runway visual range may be determined by an observer located at the end of the runway, facing in the direction of landing, or by means of a transmissomet ...

Clouds which cover between 6/10 and 9/10 of the sky. See Sky Terminology.

A numbering system using a base number of 2 and having only two digits: 0 and 1. The fundamental system of representing information with electrical pulses.

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

Cathode Ray Tube. A display element, consisting of a vacuum tube and screen, used with computers.

The maximum difference in output for any given input (within the specified range) when the value is approached first with increasing, and then with decreasing, input signals. Caused by energy absorption in the elements of the measuring instrument. Usually ...

An instrument whose calibration is determined by comparison with an absolute instrument.

A small balloon used to determine the height of the cloud base. The height can be computed from the ascent velocity of the balloon and the time required for its disappearance into the cloud.

Lacking a relationship to a time base or clock. In asynchronous communications, individual data characters are sent at an arbitrary rate.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

Same as constant-level balloon.

Same as ceiling light.

A chronograph used to make a time-record of certain measured meteorological elements. The most common type, the triple register, records wind direction and speed, duration of sunshine, and amount of rainfall (sensed respectively by a contact anemometer, M ...

An instrument, for the recording of two or more meteorological parameters, in which the ventilation is provided by a suction fan.

The direction from which the wind is blowing, measured in points of the compass or in azimuth degrees.

Anemometer which measures wind speed by the speed of rotation of 3 or 4 hemispherical or conical cups, each fixed to the end of a horizontal arm projecting from a vertical axis. See condenser-discharge anemometer, contact anemometer. Compare to bridled-cu ...

A severe weather condition characterized by low temperatures and strong winds bearing a great amount of snow, either falling or picked up from the ground.