The outer, solid portion of the earth: the crust of the earth.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

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 atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

Same as fogbow.

The record of an aneroid barograph.

A rainbow of angular radius of about 50

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

Apparatus from which the nature and time of precipitation may be determined.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

A precipitation amount of less than 0.005 inches. Also, the record made by any self-registering instrument.

A line of equal or constant temperature.

An absolute instrument developed by K. Angstrom for the measurement of direct solar radiation. The radiation receiver station consists of two identical manganin strips whose temperatures are measured by attached thermocouples. One of the strips is shaded, ...

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.