A unit of luminous intensity of a light source.

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

Very generally, any moving- stream of air. It has no particular technical connotation.

Force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

Air in motion relative to the surface of the earth. Almost exclusively used to denote the horizontal component.

Amount of solar radiation incident, per unit area and time, on a surface which is perpendicular to the radiation and is situated at the outer limit of the atmosphere, the earth being at its mean distance from the sun. It equals approximately 2.00 ly/ min ...

The intensity (flux per unit solid angle) of visible radiation weighted to take into account the variable response of the human eye as a function of the wavelength of light. Usually expressed in candles.

Psychrometer to which a small chain or rotary handle is attached so that the observer can rotate the instrument rapidly to properly ventilate the thermometer bulbs.

A wave resulting from the action of wind on a water surface.

Same as parhelion.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

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

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 ...

An instrument for measuring differences in electric potential.

A rotation anemometer in which the axis of rotation is horizontal. The instrument has either flat vanes (as in the air meter) or helicoidal vanes (as in the propeller anemometer). The relation between wind speed and angular rotation is almost linear.

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 ...

The process whereby a position on the scale of an instrument is identified with the magnitude of the signal (or input force) actuating the instrument.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

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