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

An instrument for measuring the extinction coefficient in water.

A recording pressure-tube anemometer in which the wind scale of the float manometer has been made linear by the use of springs, i.e. Dines anemometer.

See radiosonde commutator.

Solar radiation of selected wavelengths.

Same as photometer.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.

Very generally, any moving- stream of air. It has no particular technical connotation.

A remote indicator for wind speed and direction used in conjunction with a contact anemometer and a wind vane. The indicator consists of a center light, connected to the contact anemometer, surrounded by eight equally spaced lights which are individually ...

A system of designating meteorological observing stations by number. established and administered by the World Meteorological Organization. Under this scheme, specified areas of the word are divided into "blocks" each bearing a two-number designator. Stat ...

An Instrument used to determine dew point.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

A general term for instruments designed to measure the speed or force of the wind.

A self-recording thermometer.

A measure of the intensity of gusts given by the ratio of the total range of wind speed between gusts and the intermediate periods of lighter wind to the mean wind speed, averaged over both gusts and lulls.

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

A liquid-in-metal thermometer in which mercury is enclosed in a steel envelope. The change in internal pressure caused by the temperature variation is measured by a Bourdon tube which is connected to the mercury by a capillary tube. This instrument is hig ...

Federal Aviation Administration.