A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

The total of direct solar radiation and diffuse sky radiation received by a unit horizontal surface. Global radiation is measured by pyranometers.

See gain.

Eluding precise prediction, completely irregular.

Precipitation falling from a cloud, usually in wisps or streaks, but evaporating before it reaches the ground.

A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. Compare to Pit ...

Abbreviation for the pressure, temperature, and humidity data obtained by a radiosonde observation.

A definite portion of a stream channel, commonly taken between two gauging stations, but may be taken between any two specified points.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

The succession of stages through which water passes on the ground and in the atmosphere: evaporation from land or bodies of water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.

An absolute pyhrliometer, developed by C.G. Abbott, in which the radiation-sensing element is a blackened water-calorimeter.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

The difference between amounts of precipitation and runoff for a given storm. It is that portion of the precipitation that remains in the basin as soil moisture, surface storage, ground water, etc.

The total amount of water transferred to the atmosphere by evapotranspiration.

The portion of the precipitation on the land which ultimately reaches the streams. especially the water from rain or melted snow that flows over the surface.

A measure of the intensity of gusts given by the ratio of the total range of wind speed between gusts and the intermediate periods of lighter wind to the mean wind speed, averaged over both gusts and lulls.

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

The difference between the input quantity applied to a measuring instrument and the output quantity indicated by the instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

A type of wind vane having a split or V-shaped tail. The apex orients itself to the direction of the wind.

The difference between the true value of some quantity and its observed value. Every observation is subject to certain errors. Systematic errors affect the whole of a series of observations in nearly the same way. For example, the scale of an instrument m ...