A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

A curve showing the variation of temperature with height in the free air. See lapse rate.

The decrease of an atmospheric variable with height, the variable being temperature, unless otherwise specified.

See calorie.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

Facing away from the wind.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

A type of cyanometer. an instrument used to measure the blueness of the sky. The Linke-scale is simply a set of eight cards of different standardized shades of blue. They are evenly numbered 2 to 26. The odd numbers are used by the observer if he or she j ...

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.

The general term for dry atmospheric suspensoids, including dust, haze, smoke. and sand. Compare to hydrometeor.

The outer, solid portion of the earth: the crust of the earth.

A clay atmometer consisting of a hollow ceramic sphere through which evaporation occurs. Evaporation is measured by the loss of water from the reservoir which feeds the sphere.

A balloon having a detachable tail which is released when the balloon has undergone a predetermined expansion. It thus serves to measure approximately the density of the atmosphere at the point of release.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifth contact of the commutator up to a number determined by the design of the commutator. It then signals every contact except the fifth, which is ...

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.

Radiation with wavelengths greater than 4 microns. (In meteorology, same as infrared radiation.)

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.