The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

Lacking a relationship to a time base or clock. In asynchronous communications, individual data characters are sent at an arbitrary rate.

The total area drained by a river and its tributaries. Same as river basin.

Ice crystal deposits formed by sublimation (conversion of water vapor directly to ice) when temperature and dew point are below freezing.

An elongated area of relatively high pressure. Usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow. The opposite of a trough.

Any source of radiant energy, especially electromagnetic energy.

An instrument for taking photographs of an image of the sun in monochromatic light.

The decrease of an atmospheric variable with height, the variable being temperature, unless otherwise specified.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

An instrument for recording global solar radiation.

A general term for instruments which sample atmospheric suspensoids by impaction. Same as impactometer.

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 used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

Wind with a speed between 41 and 47 knots (47 and 54 mph); Beaufort scale number 9.

The record of a barograph.

A rainbow seen in the spray of the ocean. It is optically the same phenomenon as the ordinary rainbow.

A hypothetical temperature characterized by a complete absence of heat and defined as 0 K, -273.15 C, or -459.67 F.

An instrument that automatically records pressure and temperature.