The amount of precipitation captured by a rain gauge.

A general term to designate apparatus designed to observe the details of weather during thunderstorms.

Formation of a single water drop by the union of two or more colliding drops.

Automated Surface Observing System. A network of instrumented weather stations deployed primarily by the National Weather Service to make weather observations without operator involvement.

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

Same as ceiling light.

The process by which events in the real world are translated into machine-readable signals.

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.

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

In folklore, a name for rain.

A liquid-in-metal thermometer in which mercury is enclosed in a steel envelope. The change in internal pressure caused by the temperature variation is measured by a Bourdon tube which is connected to the mercury by a capillary tube. This instrument is hig ...

An instrument which indicates the presence of precipitation. The ombroscope consists of a heated, water-sensitive surface which indicates by mechanical or electrical techniques the occurrence of precipitation.

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

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

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

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

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.

An automatic, recording cloud height indicator.

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