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

A unit of energy equal to 1.356joules.

An instrument developed by K. Angstrom for measuring the effective terrestrial radiation. It consists of four manganin strips, of which two are blackened and two are polished. The blackened strips are allowed to radiate to the atmosphere while the polishe ...

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

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

The succession of stages through which water passes on the ground and in the atmosphere: evaporation from land or bodies of water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.

A very sensitive electrostatic electrometer for measuring small potential differences.

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.

Same as rain-intensity gauge.

The flux of visible radiation, so weighted as to account for the manner in which the response of the human eye varies with the Wavelength of radiation. The basic unit for luminous flux is the lumen,

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

A type of electrical thermometer in which the thermal element is a substance whose electrical resistance varies with the temperature. Such thermometers can be made with very short time constants and are capable of highly accurate measurements.

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.

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.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

The actual lifting force of an inflated balloon, usually expressed in grams.

An instrument which measures the transmissivity of the atmosphere between two points for the determination of visual range.

Instrument for measuring the intensity of radiant energy. Its principle is based on the variation of electrical resistance, with the incoming radiation, of one or both the metallic strips which the instrument comprises.