The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

Anemometer which generates an electrical contact output with a frequency proportional to wind speed.

A generic term for any machine that enables a human being to communicate with a computer.

Anemometer which measures wind speed by the speed of rotation of 3 or 4 hemispherical or conical cups, each fixed to the end of a horizontal arm projecting from a vertical axis. See condenser-discharge anemometer, contact anemometer. Compare to bridled-cu ...

in folklore, a name for fire.

A thermometer with a muslin-covered bulb which is moistened. used to measure wet-bulb temperature.

A unit of luminance (or brightness) equal to 1/6 candles per square centimeter.

A river gauge in which a weight suspended on a wire is lowered to the water surface from a bridge or other overhead structure to measure the distance from a point of known elevation to the water surface.

A systematic summary of the terms (inflow, outflow, and storage) of the storage equation as applied to the computation of soil-moisture changes, ground-water changes, etc. An evaluation of the hydrologic balance of an area. Also called basin accounting, w ...

A type of cistern barometer in which the level of mercury in the cistern is adjusted to the zero point of the scale before each reading.

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

In general. the severe wind of an intense tropical cyclone (hurricane or typhoon). The term has no further technical connotation, but, unfortunately, is easily conftlsed with the strictly defined hurricane-force wind,

The height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified as "thin" or "partial." The ceiling is termed unlimited when these conditions are not satisfied. ...

The frequency of a carrier wave.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

Same as marine rainbow.

An instrument which indicates the presence of precipitation. The ombroscope consists of a heated, water-sensitive surface which indicates by mechanical or electrical techniques the occurrence of precipitation.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

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

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...