A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

Root Mean Square. This notation is used frequently with error analysis. In that context, it is the square root of the arithmetic mean of the squares of the deviations of the individual calibration points from the theoretical or ideal response.

Precipitation from a cumuliform cloud. Characterized by the suddenness of beginning and ending, by the rapid change in intensity, and usually by a rapid change in the condition of the sky. The solid or liquid water particles are usually bigger than the co ...

A device that allows a terminal or computer at one location to communicate with a terminal or computer at a distant location via wire or phone lines.

A faintly-colored circular arc similar to a rainbow but formed on fog layers containing drops whose diameters are 100 microns or less. Also called mistbow, white rainbow.

The algebraic difference between the upper and lower limits of the measuring range of an instrument, i.e. a thermometer with a range of -35 to 50

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

An instrument for measuring the ultraviolet in solar and sky radiation.

A buoyant balloon rising freely in the atmosphere, as opposed to a captive balloon.

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

An anemometer which derives wind speed from measurements of dynamic wind pressures. Wind blowing into a tube develops a pressure greater than the static pressure, while wind blowing across a tube develops a pressure less than the static. This pressure dif ...

A type of recording siphon barometer. The mechanically magnified motion of a float resting on the lower mercury surface is used to record atmospheric pressure on a rotating drum.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

The general term for dry atmospheric suspensoids, including dust, haze, smoke. and sand. Compare to hydrometeor.

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.

The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface. In terms of the hydrologic cycle, the ...

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

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

A line of equal or constant pressure.

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