A term used to describe a sensor (or sensors), the associated transducer(s), and the data readout or recording device.

A line drawn through geographical points where a given seasonal biological event occurs on the same date.

An instrument for measuring the ultraviolet in solar and sky radiation.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

A white disk 12" or more in diameter which is lowered into the sea to estimate transparency of the water. The depths are noted at which it first disappears when lowered and reappears when raised.

A transducer which converts electromagnetic radiation in the infrared, visible, and ultraviolet regions into electrical quantities such as voltage, current, or resistance. Also called photo cell.

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.

Complementary Metal-Oxide Semiconductor. A method of making silicon chips that results in low power consumption by the circuits.

A hydrometeor consisting of a visible aggregate of minute water and/or ice particles in the atmosphere above the earth's surface. Cloud differs from fog only in that the latter is, by definition, in contact with the earth's surface.

Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.

Same as water year.

A unit that represents one degree of deviation from a reference point in the mean daily outdoor temperature (usually 65

A temperature telemeter.

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

An early and once universal name for the mercury barometer.

A captive balloon used to maintain meteorological equipment aloft at approximately a constant height. The kytoon is streamlined and combines the aerodynamic properties of a balloon and a kite.

Abbreviation for precipitation-evaporation quotient.

United Kingdom forecast model. (Available via AccuWeather.com Professional.)

See photometer.