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

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 ...

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

Board that holds graph paper on which is plotted information obtained from a pilot-balloon observation.

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

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

The time required for an instrument to registe 63.2% of a step change in the variable being measured.

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 ...

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

A seasonal wind of persistent direction, characterized by a pronounced change in direction between seasons.

A line of equal or constant pressure.

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

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.

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 type of anemometer in which the rotation of an element serves to measure the wind. Rotation anemometers are divided into two classes; those in which the axis of rotation is horizontal, such as the windmill anemometer, and those in which the axis of rota ...

See constant-level 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.

Any and all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground.