An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

An ice coating with a consistency intermediate between glaze and rime.

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.

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 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 ...

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.

A radar term for a single pulse of radio energy.

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

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

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

A recording variometer.

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

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

Readily taking up and retaining moisture.

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.

Same as freezing point.

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

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

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

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 ...