Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

The process of modifying some characteristic of a wave (the carrier) so that it varies in step with the instantaneous value of another wave (the modulating wave) in order to transmit a message. The modified characteristic may be frequency, phase, and/or a ...

The difference between the solar radiation directed downward and upward; net flux of solar radiation.

Ice crystal deposits formed by sublimation (conversion of water vapor directly to ice) when temperature and dew point are below freezing.

check chamber-A chamber use to check the sensing elements of radiosonde equipment.

Wind with a speed between 4 and 27 knots (4 and 31 mph); Beaufort scale numbers 2 through 6.

Same as Aeolian.

force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

The difference between the air temperature and the dew-point. Also called dew-point deficit, dew-point depression.

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 ...

That stage, on a fixed river gauge, at which overflow of the natural banks of the stream begins to cause damage in any portion of the reach for which the gauge is used as an index.

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

A unit measure of electrical conduction. The facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow. Electrical conductivity is the reciprocal of electric ...

Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed.

Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.

A temperature-sensing element which converts thermal energy directly into electrical energy. In its basic form it consists of two dissimilar metallic conductors connected in a closed loop. Each junction forms a thermocouple. If one thermocouple is maintai ...

See stage.

Thermometer used for measuring the highest temperature attained during a given interval of time, for example, a day.