A rainbow formed by light rays which have been reflected from an extended water surface. Not to be confused with a reflected rainbow whose image may be seen in a still body of water. The center of a reflection rainbow is at the same elevation as the sun b ...

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves. T ...

An instrument for measuring the extinction coefficient in water.

Small particle on which water vapor condenses.

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

A photometric unit of illuminance or illumination equal to one lumen per square meter

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

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.

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

An evaluation of upper air temperature, pressure, and humidity from radio signals received from a balloon- borne radiosonde.

Same as wave pole.

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.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

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

Abbreviation for mean sea level.

Having a specific relationship to a time base or clock. In synchronous communications, data characters are sent according to a timing signal which synchronizes the two communicating devices.

Value of soil moisture, expressed as a percentage of the mass of dry soil, below which a plant living in the soil dies by wilting.

A transducer for converting thermal energy directly into electrical energy. It is composed of pairs of thermocouples which are connected either in series or in parallel. Thermopiles are used in thermoelectric radiation instruments when the output of a sin ...

A device used to hold liquid-in-glass maximum and minimum thermometers in the proper recording position inside an instrument shelter, and to permit them to be read and reset. See Townsend support.