Determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.

The volume of liquid water evaporated per unit area in unit time. usually measured as the depth of liquid water lost per unit time from the whole area.

See calorie.

An anemometer which measures wind speed in terms of the drag which the wind exerts on a solid body. See bridled-cup anemometer, normal-plate anemometer, pendulum anemometer.

The water portion of the earth as distinguished from the solid part, called the lithosphere, and from the gaseous outer envelope, called the atmosphere.

Thermometer in which the difference in the rates of expansion with temperature of a liquid and its receptacle is used as a measure of the temperature. The liquid used may be ethyl alcohol, toluene, petroleum, or mercury.

A small, limited-capacity central processing unit contained entirely on one semiconductor chip.

Same as ombrometer.

General term for any device that measures precipitation: principally a rain gauge or snow gauge.

A standard interface between a computer input/output port and a peripheral device. Signal properties including time duration, voltage. and current, are specified by the Electronic Industries Association.

Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e. cubic feet per second.

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.

A hypothetical body which absorbs some constant fraction, between zero and one, of all electromagnetic radiation incident upon it, which fraction is the absorptivity and is independent of wavelength. Compare to black body, white body.

A measure of luminous flux remaining in a light beam after it has passed through a specified distance of the atmosphere.

A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.

A measure of the intrinsic luminous intensity emitted by a source in a given direction. Luminance is a measure only of light. The comparable term for electromagnetic radiation in general is radiance.

A line drawn through geographical points having the same pluvial index.

Solar and terrestrial radiation directed downwards (towards the earth's surface); incoming radiation.

Companion to the wet-bulb thermometer in a psychrometer. Used to measure ambient air temperature.

meter-An instrument for measuring the transmissivity of the atmosphere; a type of transmissometer. It consists of a constant- intensity collimated light source located at a suitable distance from a photoelectric cell. Variation in the turbidity of the atm ...