An instrument for determining the dust content of a sample of air. Also spelled conimeter.

A graphical representation of stage or discharge at a point on a stream as a function of time.

A power supply which achieves its output regulation by means of one or more active power handling devices which are alternately placed in the "off" or "on" states. It is more efficient than linear supplies which vary the conduction of power devices to ach ...

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 ...

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

The condition of the atmosphere when the amount of water vapor present is the maximum possible at the existing temperature.

The level at which ice crystals and snowflakes melt as they descend through the atmosphere.

An early and once universal name for the mercury barometer.

A colorless and odorless gaseous element. The lightest and apparently the most abundant chemical element in the universe. However, it is found only in trace quantities in the observable portion of our atmosphere, only about 0.00005 percent by volume of dr ...

variable audio-modulated radiosonde developed at the Bureau of Standards and used by the United States weather services.

A type of precipitation composed of unbranched crystals in the form of needles, columns, or plates. Usually has a very slight downward motion and may fall from a cloudless sky.

The true freezing point of water. The temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere.

The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

Same as constant-level balloon.

Sir Napier Shaw's name for the approximate absolute temperature scale,

A measurement of atmospheric conditions aloft, above the effective range of a surface weather observation. Elements evaluated include temperature, humidity, pressure, wind speed, and wind direction.

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.

A high-altitude sounding system consisting of a small solid- propellant research rocket carried aloft by a large plastic balloon. The rocket is fired near the maximum altitude of the balloon flight.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

Situated on the side from which the wind blows.