A device, similar to a potometer, for measuring transpiration, consisting of a vessel containing soil in which one or more plants are rooted and sealed so that water can escape only by transpiration from the plant.

An instrument for measuring the intensity of light or the relative intensity of a pair of lights. Also called an illuminometer. If the instrument is designed to measure the intensity of light as a function of wavelength, it is called a spectrophotometer. ...

An automatic, recording cloud height indicator.

A reversing thermometer which is encased in a strong glass outer shell that protects it against hydrostatic pressure. Compare to unprotected thermometer.

A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

Dihydrogen oxide, molecular formula H2O.

An old nautical term for mercury barometer.

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.

The general term for dry atmospheric suspensoids, including dust, haze, smoke. and sand. Compare to hydrometeor.

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

A unit of luminous intensity of a light source.

A method of winds aloft observation accomplished by tracking a balloon-borne radar target or radiosonde with either radar or a radio theodolite.

A coating of ice, generally clear and smooth. formed by the freezing of supercooled water on a surface.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

Abbreviation for precipitation effectiveness index.

Same as windsock.

A type of climatic diagram whose coordinates are some form of temperature vs. a form of humidity or precipitation.