A small, moveable graduated scale adjacent and parallel to the main scale of an instrument. It provides a means for interpolating between the graduations of the main scale.

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 ...

A device which automatically records the water equivalent of snow on a given surface as a function of time. A small sample of a radioactive salt is placed in the ground in a shielded collimator which directs a beam of radioactive particles upwards. A Geig ...

Same as humidity strip.

Programs or instructions which are stored in readonly memory.

An instrument for measuring radiant energy. See actinometer, Dines radiometer, photometer, Tulipian radiometer.

A systematic observational error due to the characteristics of the observer. The uncertainty in a reading made by an observer may be acertained by a statistical analysis of his or her readings.

An instrument for measuring the extinction coefficient in water.

The addition of one or more redundant bits to information to verify its accuracy.

That temperature at which, in a specified latitude, the reading of a particular barometer requires no temperature or latitude correction.

A type of electrical thermometer consisting of two thermocouples which are series-connected with a potentiometer and a constant-temperature bath. One couple, called the reference junction, is placed in a constant-temperature bath, while the other is used ...

An instrument which measures the spectral distribution of the intensity of direct solar radiation.

Small particle on which water vapor condenses.

Navy Operational Global Atmospheric Prediction System. A global meteorological model operated by the Department of Defense.

Same as wave pole.

A pyranometer developed by M. Robitzsch. Its design utilizes three bimetallic strips which are exposed horizontally at the center of a hemispherical glass bowl. The outer strips are white reflectors and the center strip is a blackened absorber. The bimeta ...

National Centers for Environmental Prediction. Central computer and communications facility of the National Weather Service; located in Washington, DC.

A semiconductor which exhibits rapid and extremely large changes in resistance for relatively small changes in temperature.

A balloon-borne instrument for the simultaneous measurement and transmission of meteorological data. It includes transducers for the measurement of pressure, temperature, and humidity; a modulator for the conversion of the output of the transducers to a q ...

Barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.