Frozen or partly frozen rain.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

A liquid-in-glass thermometer which uses an organic substance such as alcohol as the thermometer liquid. This type of thermometer has a low freezing point and a high coefficient of expansion. It is less accurate, however, than a mercury thermometer.

A method of upper air observation consisting of an evaluation of the wind speed and direction, temperature, pressure, and humidity aloft by means of a balloon-borne radiosonde tracked by radar or a radio theodolite.

Read Only Memory. A memory that cannot be altered in normal use of a computer, Usually used to store information permanently, such as firmware programs.

A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.

Same as Aeolian.

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.

Name sometimes given to a transmissometer.

See hook gauge.

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 generic term for any machine that enables a human being to communicate with a computer.

Lowest altitude in the atmosphere over a given location at which the air temperature is 0

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.

A number of quantity defining a limit that errors will not exceed when a device is used under specified operating conditions. Accuracy rating can be expressed in a number of forms, i.e. in terms of the measured variable (+/- 1 C), percent of span (+/-0.5% ...

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

A method of streamflow routing which assumes that storage is a linear function of the weighted flow in the reach and is adaptable to a simple mathematical solution.

Binary Coded Decimal. A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

A measure of the attenuation due to scattering, of light as it traverses a medium containing scattering particles.