A hygrometer based upon the diffusion of water vapor through a porous membrane.

A graphical aid used in the reduction of data from a winds aloft observation.

Old snow that has become granular and compacted as a result of melting and refreezing.

A spring which is designed to achieve a fixed spring constant over a wide temperature range. Usually, this involves an alloy with high nickel content such as Ni-Span C. It is common for these springs to be stress relieved at elevated temperature after for ...

See Koschmieder's law.

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

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.

Name applied to a class of instruments which measure the liquid content of the atmosphere.

The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air. Obtained by evaporation of water (or ice) from the muslin wick. Used in computing dew point and relative humidity.

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

An instrument which determines the altitude of an object with respect to a fixed level. There are two general types of altimeters: (a) the pressure altimeter, which gives an approximate measure of altitude from a pressure measurement and an assumed standa ...

Same as luminous intensity.

An ice coating with a consistency intermediate between glaze and rime.

A continuous-recording barometer.

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

A computed characteristic of a particular river basin, expressed as the time difference between the time-center of mass of rainfall and the time-center of mass of resulting runoff.

A particular pattern of snow sampler having an internal diameter of 1.485 inches so that each inch of water in the sample weighs one ounce.

Same as precipitation-evaporation ratio.

An instrument for measuring the extinction coefficient in water.

The addition of one or more redundant bits to information to verify its accuracy.