A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

The value of atmospheric pressure to which the scale of a pressure altimeter is set so as to indicate airport elevation. The altimeter setting is included as part of an aviation weather observation.

A Sunshine recorder of the type in which the time scale is supplied by the motion of the sun. The instrument, which is pointed at the celestial pole, consists of a hemispherical mirror mounted externally on the optical axis of a camera. The lens of the ca ...

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

A reversing thermometer (for seawater temperature) which is not protected against hydrostatic pressure. The mercury bulb is therefore squeezed, and the amount of mercury broken off on reversal is a function of both temperature and of hydrostatic pressure.

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

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

Instrument for measuring the intensity of radiant energy. Its principle is based on the variation of electrical resistance, with the incoming radiation, of one or both the metallic strips which the instrument comprises.

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

A radar term for a single pulse of radio energy.

A recording variometer.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

Readily taking up and retaining moisture.

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

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 ...

A relatively small-scale, upward moving current of air.

A balloon designed to float at a constant pressure level. This may be accomplished by a pressure valve which controls the release of ballast so as to maintain flight above a selected pressure level until the supply of ballast is exhausted. See Moby Dick b ...

Same as freezing point.

Temperature of equilibrium between the liquid and vapor phases of a substance at a given pressure.

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.