An instrument used to reveal but not necessarily measure the presence of an electrical quantity. It is used to display the output of a sensing element after suitable amplification and modification. Sometimes called display.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

Area of a computer or other device where various logic and control elements are interconnected. Often a printed circuit board into which other circuit boards plug at right angles.

A unit of power equal to one joule per second or 10' ergs per second.

A graduated scale placed in a position so that the stage of a stream may be read directly from it. Staff gauges may be placed on bridge piers or pilings, etc., or placed on specially constructed supports.

A component of a radiosonde consisting of a series of alternate electrically conducting and insulating strips. As these are scanned by a contact the radiosonde transmits temperature and humidity signals alternately. The contact may be a baroswitch as in t ...

A temperature telemeter.

Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval. Also called fluctuation velocity.

An instrument used to measure the water vapor content of the air.

See calorie.

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 ...

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

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

Wind with a speed between 28 and 33 knots (32 and 38 mph); Beaufort scale number 7.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

Any twelve-month period, usually selected to begin and end during a relative dry season. Used a basis for processing streamflow and other hydrologic data. The period from October 1 to September 30 is widely used in the U.S.

See stage.