Same as atmometer.

Any source of radiant energy, especially electromagnetic energy.

Board that holds graph paper on which is plotted information obtained from a pilot-balloon observation.

A photoelectric spectrophotometer which is used in the determination of the ozone content of the atmosphere.

A hygrometer which uses a transducing element whose electrical properties are a function of atmospheric water vapor content. The humidity strip and carbon-film hygrometer element are examples of such a transducer.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

An instrument used to measure the water vapor content of the air.

See constant-level balloon.

See foehn.

See ceilometer.

A high-altitude sounding system consisting of a small solid- propellant research rocket carried aloft by a large plastic balloon. The rocket is fired near the maximum altitude of the balloon flight.

Upwarddirected solar radiation, reflected by the earth's surface and the atmosphere.

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

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 ...

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

A unit measure of electrical conduction. The facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow. Electrical conductivity is the reciprocal of electric ...

Temperarure at which a liquid solidifies under any given set of conditions. It may or may not be the same as the melting point or the more rigidly defined true freezing point or (for water) ice point.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine by the action of the sun's rays upon blueprint paper. A type of sunshine recorder.

A line of equal or constant pressure.