The gravity flow of water within soil.

An anemometer which derives wind speed from measurements of dynamic wind pressures. Wind blowing into a tube develops a pressure greater than the static pressure, while wind blowing across a tube develops a pressure less than the static. This pressure dif ...

Pertaining to measurements or devices in which the output vanes in discrete steps, i.e. on-off or pulse signals. Compare to analog.

A basic equation in daytime visual range theory, relating the apparent luminance of a distant black object, the apparent luminance of the background sky above the horizon, and the extinction coefficient of the atmosphere, or the air layer near the ground. ...

Name sometimes given to a transmissometer.

Lowest altitude in the atmosphere over a given location at which the air temperature is 0

The maximum rate at which precipitation can pass through the surface into the soil, for a given soil in a given condition.

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source. Direct solar radiation is measured by pyrheliometers.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

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

Temperature based on an absolute scale.

By international agreement, a period during which greatly increased observation of world-wide geophysical phenomena is undertaken through the co-operative effort of participating nations. July 1957-December 1958 was the first such year. However, precedent ...

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

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 ...

A hygrometer using goldbeater's skin as the sensitive element. Variations of the physical dimensions of the skin caused by its hygroscopic character indicate relative humidity. (Note: Goldbeater's skin is the prepared outside membrane of the large intesti ...

A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.

A measure of the amount of "spin" (or rotation) in the atmosphere.

The total area drained by a river and its tributaries. Same as river basin.

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