Balance of the water resources of a region, comparing precipitation and inflow with outflow, evaporation, and accumulation.

A hypothetical temperature characterized by a complete absence of heat and defined as 0 K, -273.15 C, or -459.67 F.

A semiconductor which exhibits rapid and extremely large changes in resistance for relatively small changes in temperature.

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

Any wind blowing down an incline. If warm, it is a foehn. If cold, it may be a fall wind or a gravity wind.

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

See hydrologic accounting.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

A thermometer. the sensitive element of which consists of two metal strips which have different coefficients of expansion and are brazed together. The distortions of the system in response to temperature variations are used as a measure of temperature. It ...

General term for any device that measures precipitation: principally a rain gauge or snow gauge.

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

A feeble oscillatory disturbance of the earth's crust, detectable only by very sensitive seismographs. Certain types of microseisms seem to be closely correlated with pressure disturbances. See microbarm.

A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.

Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.

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

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine by the action of the sun's rays upon blueprint paper. A type of sunshine recorder.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

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.