Same as mercury barometer.

The officially designated elevation of an airport above mean sea level, taken as the highest point on any of the runways of the airport. Same as airport elevation.

An instrument used to measure and record earthquake vibrations and other earth tremors.

See gust and peak gust.

The total infrared radiation emitted from the earth's surface. To be carefully distinguished from atmospheric radiation, effective terrestrial radiation, and insolation.

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 maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

An apparatus, used in studying soil temperatures, for measuring the total supply of heat during a given period.

The element directly responsive to the value of the measured variable.

The visibility along an identified runway, determined from a specified point on the runway with the observer facing in the same direction as a pilot using the runway. Compare to runway visible range.

Any one of a family of circular arcs consisting of concentric colored bands, arranged from red on the inside to blue on the outside, which may be seen on a "sheet" of water drops (rain, fog, spray). The most common of the many possible is the primary rain ...

An instrument that shows changes in humidity.

A mercury barometer which measures atmospheric pressure by weighing the mercury in the column or cistern.

Dihydrogen oxide, molecular formula H2O.

The difference between the outgoing infrared terrestrial radiation of the earth's surface and the downcoming infrared counterradiation from the atmosphere.

That portion of the atmosphere which is above the lower troposphere. Generally applied to levels above 850 mb.

Wind with a speed between 48 and 55 knots (55 and 63 mph), Beaufort scale number 10.

Contraction for radiosonde observation.