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

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.

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.

The greatest distance at which it is just possible to see and recognize with the unaided eye (1) in the daytime, a prominent dark object against the sky at the horizon, and (2) at night, a known, preferably unfocused, moderately intense light source.

A mercury barometer in which the lower mercury surface is larger in area than the upper surface. The basic construction of a cistern barometer is as follows: A glass tube one meter in length, sealed at one end is filled with mercury, and then inverted. Th ...

For a given cloud or cloud laver. the lowest level in the atmosphere at which the air contains a perceptible quantity of cloud particles.

An instrument of the aspiration condenser type which measures the concentration and mobility of small ions.

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

The amount of precipitation captured by a rain gauge.

A recording anemometer.

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

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

A forecast of weather elements of particular interest to aviation; including ceiling, visibility, upper winds, icing, turbulence, precipitation types, and storms.

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

The correction applied to an instrument to account for the effect of temperature upon its response characteristics.

The general term for anemometers operating on the principle that the heat transfer to air from an object at an elevated temperature is a function of the air speed. Examples are the hot-wire anemometer and the katathermometer.

Physical equipment used in data processing. Compare to firmware, software.

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

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

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