The size of the area comprising a watershed or river basin. Also called catchment area.

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

Any meteorological instrument, such as a radiosonde, in which the recording apparatus is located at some distance from the measuring apparatus.

The unit of speed in the nautical system; one nautical mile per hour. It is equal to 1.1508 statute miles per hour or 0.5144 meters per second.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

An instrument for the measurement of both solar and terrestrial radiation.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

A c.g.s. (centimeter-gram-second) unit of mass. Originally defined as the mass of 1 cubic centimeter of water at 4

The limiting values of ceiling, visibility, and wind, or runway visual range, established as safety minimum for aircraft landings and take-offs.

A reflecting type telescope with a 45

variable audio-modulated radiosonde developed at the Bureau of Standards and used by the United States weather services.

A temperature scale on which the freezing point of water equals 32

A unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

The total of direct solar radiation and diffuse sky radiation received by a unit horizontal surface. Global radiation is measured by pyranometers.

The amount of moisture which, if available, would be removed from a given land area by evapotranspiration. Expressed in units of water depth.

Programs or instructions which are stored in readonly memory.

A cup anemometer with its shaft mechanically coupled to a magneto.

A seasonal wind of persistent direction, characterized by a pronounced change in direction between seasons.

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.