See hurricane beacon.

A type of wind vane having a split or V-shaped tail. The apex orients itself to the direction of the wind.

The record or trace made by a microbarograph.

A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

An instrument for measuring the ultraviolet in solar and sky radiation.

A unit of distance equal to 5280 feet. It is sometimes referred to as a land mile.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

A record obtained from a meteorograph. A chart in which meteorological variables are plotted against time.

The time required for an instrument to registe 63.2% of a step change in the variable being measured.

A box-like structure designed to protect certain meteorological instruments from exposure to direct sunlight, precipitation, and condensation, while at the same time providing adequate ventilation. Instrument shelters are painted white, have louvered side ...

A defective maximum thermometer of the liquid-inglass type in which the mercury flows too freely through the constriction. Such a thermometer will indicate a maximum temperature that is too low.

A hygrometer based upon the diffusion of water vapor through a porous membrane.

Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system. Compare to adiabatic process.

A rocket designed primarily for routine upper air observations in the lower 250,000 feet of the atmosphere, especially that portion inaccessible to balloons (above 100,000 feet).

Thermometer for measuring the temperature in the soil at different depths.

The quantity to be measured (or modulated, or detected, or operated upon) which is received by an instrument. Thus, for a thermometer. temperature is the input quantity.

A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

variable audio-modulated radiosonde developed at the Bureau of Standards and used by the United States weather services.

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 ...