A surface weather observation, made at periodic times, of sky cover, state of the sky, cloud height, atmospheric pressure reduced to sea level, temperature, dew point, wind speed and direction. amount of precipitation, hydrometeors and lithometeors. and s ...

Air in motion relative to the surface of the earth. Almost exclusively used to denote the horizontal component.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

The record or trace made by a microbarograph.

Solar radiation of selected wavelengths.

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

An instrument resulting from the combination of a thermograph and a hygrograph and furnishing, on the same chart, simultaneous time recording of ambient temperature and humidity.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

See sea-water thermometer, reversing thermometer.

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

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

A thermometer based upon the principle that the velocity of a sound wave is a function of the temperature of the medium through which it passes. Sonic thermometers possess very short time-constants and eliminate radiation error.

Eluding precise prediction, completely irregular.

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.

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 ...

A recording weight barometer.

A spring which is designed to achieve a fixed spring constant over a wide temperature range. Usually, this involves an alloy with high nickel content such as Ni-Span C. It is common for these springs to be stress relieved at elevated temperature after for ...

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifth contact of the commutator up to a number determined by the design of the commutator. It then signals every contact except the fifth, which is ...

A cup anemometer with its shaft mechanically coupled to a magneto.