An instrument for determining the degree of polarization of light. See photopolarimeter.

An instrument for taking photographs of an image of the sun in monochromatic light.

Wind with a speed between 28 and 33 knots (32 and 38 mph); Beaufort scale number 7.

That stage, on a fixed river gauge, at which overflow of the natural banks of the stream begins to cause damage in any portion of the reach for which the gauge is used as an index.

A rain gauge which is placed under trees or foliage to determine the rainfall in that location. By comparing this catch with that from a rain gauge set in the open. the amount of rainfall which has been intercepted by foliage can be determined.

An instrument for measuring the relative speed of a fluid. It consists of a concentric pipe arrangement in which the inner pipe is open at one end and the outer pipe is perforated and closed at both ends. Each pipe is connected to a manometer. The unit is ...

By international agreement, a period during which greatly increased observation of world-wide geophysical phenomena is undertaken through the co-operative effort of participating nations. July 1957-December 1958 was the first such year. However, precedent ...

Pertaining to rain, or more broadly, to precipitation.

Same as precipitation-evaporation ratio.

A line drawn through all points on a map having the same amount of cloudiness.

See foehn.

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

A line drawn through points of equal humidity on given surface.

A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

Determination of the total amount of snow covering a watershed or a given region. Both depth and water content of the snow may be measured, and the results may be used to predict the amount of water that will be available after melting.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.

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. ...

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.

The most common of the principal rainbow phenomena, which appears as an arc of about 42