A thermometer whose sensitive element has been made to resemble a black body by covering it with lamp black. The thermometer is placed in an evacuated transparent chamber which is maintained at a constant temperature. The instrument responds to insolation ...

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

The value of the quantity measured, as indicated or otherwise provided by a measuring instrument.

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

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

A thermopile used in some types of radiation instruments. See solarimeter.

The statement that the viscosity of air is independent of the density of air.

The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface. In terms of the hydrologic cycle, the ...

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

A radar which is used to obtain the azimuth elevation, and slant range of an airborne target.

A protective coating applied to circuits.

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

The visibility along an identified runway, determined from a specified point on the runway with the observer facing in the same direction as a pilot using the runway. Compare to runway visible range.

Same as freezing point.

A wind vane used to obtain the horizontal and vertical components of the wind.

The writing component of a recording instrument.

A line drawn through points of equal humidity on given surface.

See foehn.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface. This result of infrared (long-wave) absorption and reemission by the atmosphere is the principal factor in the greenhouse effect.