An instrument for measuring the ultraviolet in solar and sky radiation.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

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.

The time required for an instrument to registe 63.2% of a step change in the variable being measured.

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

Amount of solar radiation incident, per unit area and time, on a surface which is perpendicular to the radiation and is situated at the outer limit of the atmosphere, the earth being at its mean distance from the sun. It equals approximately 2.00 ly/ min ...

A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

A mercury-in-glass thermometer which records the temperature upon being inverted and retains its reading until being returned to the first position.

A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

A seasonal wind of persistent direction, characterized by a pronounced change in direction between seasons.

The lowest value of a measured quality at which a sensor meets its accuracy specification.

An atmometer which uses a filter paper disc as the evaporating element. The amount of water evaporated through the paper is read at the graduated tube reservoir.

A unit of energy equal to 1.356joules.

An instrument used to measure the water vapor content of the air. A type of hygrometer. It consists of a wet-bulb and a dry-bulb thermometer. See aspiration psychrometer, Assmann psychrometer. hygrodeik, sling psychrometer.

A defective maximum thermometer of the liquid-inglass type in which the mercury flows too freely through the constriction. Such a thermometer will indicate a maximum temperature that is too low.

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

A measure of long-term precipitation effectiveness. The ratio of the normal annual rainfall to the normal annual evaporation.

The total amount of water transferred to the atmosphere by evapotranspiration.

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

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