A general term to designate apparatus designed to observe the details of weather during thunderstorms.

A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

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

Infrared radiation emitted by or being propagated through the atmosphere.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

An instrument which measures the intensity of radiation by determining the amount of chemical change( or fluorescence produced by that radiation.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

An instrument developed by K. Angstrom for measuring the effective terrestrial radiation. It consists of four manganin strips, of which two are blackened and two are polished. The blackened strips are allowed to radiate to the atmosphere while the polishe ...

Same as dew-point hygrometer.

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.

Frozen or partly frozen rain.

A hypothetical, ideal body which absorbs completely all incident radiation. independent of wavelength and direction. No actual substance behaves as a true black body, although platinum black and other soots rather closely approximate this ideal. However, ...

Downward-facing pyranometer used for measuring reflected solar radiation.

Same as instrument shelter.

A method of upper air observation consisting of an evaluation of the wind speed and direction, temperature, pressure, and humidity aloft by means of a balloon-borne radiosonde tracked by radar or a radio theodolite.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

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.

Clouds which cover between 6/10 and 9/10 of the sky. See Sky Terminology.