Board that holds graph paper on which is plotted information obtained from a pilot-balloon observation.

The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface. In terms of the hydrologic cycle, the ...

A device, similar to a phytometer, for measuring transpiration. It consists of a small vessel containing water and sealed so that the only escape of moisture is by transpiration from a leaf, twig, or small plant with its cut end inserted in the water.

See mote.

A unit of energy equal to 1.356joules.

The atmospheric pressure computed using station elevation as the reference datum level. Station pressure is usually the base value from which sea level pressure and altimeter setting are determined.

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

Same as parhelion.

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.

Same as water year.

An elongated area of relatively low atmospheric pressure. Usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow. The opposite of a ridge.

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

Solar radiation of selected wavelengths.

The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

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

A device for computing certain psychrometric data, usually the dew point and the relative humidity, from known values of the dry-bulb and wet-bulb temperatures and the atmospheric pressure. One type is the circular slide-rule form and, like the psychromet ...

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

A polarimeter utilizing a Wollaston prism as a polarizer and a Nicol prism as an analyzer.

A line of equal or constant temperature.

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