The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the mass of dry air. For many purposes, the mixing ratio may be approximated by the specific humidity.

An instrument for recording global solar radiation.

An instrument whose calibration is determined by comparison with an absolute instrument.

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

Overflowing by water of the normal confines of a stream or other body of water, or accumulation of water by drainage over areas which are not normally submerged.

See gust and peak gust.

Determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...

An instrument used to reveal but not necessarily measure the presence of an electrical quantity. It is used to display the output of a sensing element after suitable amplification and modification. Sometimes called display.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

A unit of power equal to one joule per second or 10' ergs per second.

A psychrometer in which the ventilation is provided by a suction fan.

An anemometer utilizing the principle that the pitch of the aeolian tones generated by air moving past an obstacle is a function of the speed of the air. Largely a curiosity and has been put to no practical application in modem meteorology.

A fixed support for mounting maximum and minimum thermometers of the liquid-in-glass type. The support holds the thermometers at the correct operating attitude and also permits their rotation for resetting when desired.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the total mass of the system.

A thermometer designed for use in measuring the temperature of sea water. One form consists of a mercury-in-glass thermometer protected by a perforated metal case. Another form consists of a mercury-in-glass thermometer surrounded by a metal case which fo ...

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

Occupational Safety and Health Administration. A regulatory office of the U.S. Department of Labor.

modulated radiosonde-A radiosonde which transmits the indications of the meteorological sensing elements in the form of pulses spaced in time. The meteorological data are evaluated from the intervals between the pulses. Also called timeinterval radiosonde ...