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

Same as wind sock.

An instrument for measuring the extinction coefficient in water.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

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

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.

In folklore, a name for wind.

Any sudden and heavy rain, almost always of the shower type.

Downward-facing pyranometer used for measuring reflected solar radiation.

A thermodynamic change of state in a system in which there is no transfer of heat or mass across the boundaries of the system. In an adiabatic process, compression always results in warming, expansion in cooling. Compare to diabatic process.

Movernent of water through the soil surface into the soil, or the quantity of water entering the soil. Infiltration is equal to the total precipitation less the losses due to interception by vegetation. retention in depressions on the land surface, evapor ...

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

Abbreviation for Instrument Flight Rules, but commonly used to refer to the weather and/or flight conditions to which these rules apply, i.e. low visibility.

Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...

A device which surrounds a rain gauge and acts to maintain horizontal flow in the vicinity of the funnel so that the catch will not be influenced by eddies generated near the gauge. See Alter shield, Nipher shield, Wild fence.

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

Same as instrument shelter.

Name applied to a class of instruments which measure the liquid content of the atmosphere.

See wind vane.