A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

A small, limited-capacity central processing unit contained entirely on one semiconductor chip.

An instrument used to measure and record earthquake vibrations and other earth tremors.

The number of cycles per second between the limits of a frequency band.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

Precipitation composed of liquid water drops more than 0.5 mm in diameter, failing in relatively straight, but not necessarily vertical, paths. Compare to drizzle.

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.

A special form of the aspiration psychrometer. developed by Assmann, in which the thermometric elements are well shielded from radiation. Psychrometric measurements may be taken with the instrument in the presence of direct solar radiation.

General name for an instrument which measures the earth's magnetic field intensity.

An instrument used for measuring the specific gravity of a liquid.

Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.

A measurement of atmospheric conditions aloft, above the effective range of a surface weather observation. Elements evaluated include temperature, humidity, pressure, wind speed, and wind direction.

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

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

Same as contact anemometer.

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.