See mote.

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.

Any and all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground.

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.

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

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

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

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

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

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 unit of energy equal to 1.356joules.

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

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

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

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.

See hurricane beacon.

A forecast of the expected stage or discharge at a specified time, or of the total volume of flow within a specified Interval of time, at one or more points along a stream.

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.