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.

A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.

A synoptic code approved by the World Meteorological Organization in which the observable meteorological elements are encoded and transmitted in "words" of five numerical digits length. Often abbreviated synoptic code.

A thermopile used in some types of radiation instruments. See solarimeter.

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

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

See stage.

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

A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

A type of modulation in which the frequency of a continuous radio carrier wave is varied in accordance with the properties of a second (modulating) wave.

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

A mercury barometer in which the tube is U-shaped and the upper and lower mercury surfaces have the same diameter.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

A graphical representation of stage or discharge at a point on a stream as a function of time.

The point (physical and/or electrical) where two distinct data processing elements meet.

See foehn.

A pressure tube anemometer, consisting of a pitot tube mounted on the windward end of a wind vane and a suitable manometer to measure the developed pressure and calibrated in units of wind.

A unit of luminance or brightness equal to 1/d candles per foot'.

A rotation anemometer which has a horizontal axis upon which helicoidal shaped vanes are mounted. See windmill anemometer.

A method of winds aloft observation in which the elevation and azimuth angles of a theodolite are read while visually tracking a pilot balloon. Balloon height data is estimated from assumed balloon ascension rates.