The process in which incident radiation is retained by a substance. A further process always results from absorption.

The greatest distance at which it is just possible to see and recognize with the unaided eye (1) in the daytime, a prominent dark object against the sky at the horizon, and (2) at night, a known, preferably unfocused, moderately intense light source.

A large plastic constant-level balloon for duration flying (in excess of 24 hours) at altitudes above 40,000 feet, used for the determination of wind fields and the measurement of upper atmospheric parameters.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

An instrument for measuring the extinction coefficient in water.

A small balloon used to determine the height of the cloud base. The height can be computed from the ascent velocity of the balloon and the time required for its disappearance into the cloud.

Pertaining to measurements or devices in which the output varies continuously, i.e. voltage or rotation signals. Compare to digital.

The study of waters (including oceans, lakes, and rivers) embracing either: (a) their physical characteristics, from the standpoint of the oceanographer or limnologist; or (b) the elements affecting safe navigation, from the point of view of the mariner. ...

Electromagnetic radiation lying in the wavelength interval between 0.8 micron and I millimeter. At the lower limit of this interval, the infrared radiation spectrum is bounded by visible radiation, while on its upper limit it is bounded by microwave radia ...

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

Eluding precise prediction, completely irregular.

A precipitation gauge consisting of a receiver in the shape of a funnel which empties into a bucket mounted upon a weighing mechanism. The weight of the catch is recorded as inches of precipitation.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

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

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

The temperature registered by a thermometer with its bulb at the level of the tops of the grass blades in short turf.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

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

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.