The wind speed and direction at various levels in the atmosphere above the level reached by surface weather observations.

An instrument used for measuring geometric angles. See radio direction-finder.

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

An absolute temperature scale with the degree of the Fahrenheit scale and the zero point of the Kelvin scale. The freezing point of water equals 491.69

See calorie.

Same as fogbow.

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

A curve showing the variation of temperature with height in the free air. See lapse rate.

A wind blowing in a direction perpendicular to the course of a moving object.

Precipitation caused by the ascent of moist air over an orographic barrier such as a Mountain range.

An instrument for recording global solar radiation.

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.

See radar theodolite, radio direction-finder.

The level at which ice crystals and snowflakes melt as they descend through the atmosphere.

Solar radiation scattered by particles in the atmosphere.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.