A thermometer. the sensitive element of which consists of two metal strips which have different coefficients of expansion and are brazed together. The distortions of the system in response to temperature variations are used as a measure of temperature. It ...

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

A curve showing the variation of temperature with height in the free air. See lapse rate.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

Automated Surface Observing System. A network of instrumented weather stations deployed primarily by the National Weather Service to make weather observations without operator involvement.

The programs and instructions which direct a computer.

A continuous-recording barometer.

An instrument for measuring differences of electric potential.

A graduated scale placed in a position so that the stage of a stream may be read directly from it. Staff gauges may be placed on bridge piers or pilings, etc., or placed on specially constructed supports.

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

See hydrologic accounting.

An instrument for studying, or examining substances in, polarized light. See Savant polariscope.

The amount of precipitation captured by a rain gauge.

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

A hydrometeor consisting of a visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface.

A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.

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.

In general, any self-recording instrument carried aloft by any means to obtain meteorological data.

A cover which fits over a large inflated balloon to facilitate handling in high or gusty winds.

A recording hair hygrometer.