Either of two colored luminous spots that appear at points 22

Barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.

A measure of the intrinsic luminous intensity emitted by a source in a given direction. Luminance is a measure only of light. The comparable term for electromagnetic radiation in general is radiance.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

The processing of the form or mode of a signal so as to make it intelligible to, or compatible with, a given device.

An instrument for collecting liquid water from the atmosphere.

The total electromagnetic radiation emitted by the sun. About 99.9 percent of its energy output falls within the wavelength interval from 0. 15 microns to 4.0 microns, with peak intensity near 0.47 microns. About one-half of the total energy in the solar ...

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

Tables prepared from the psychrometric formula and used to obtain vapor pressure, relative humidity, and dew point from values of wet-bulb and dry-bulb temperatures.

An instrument that shows changes in humidity.

A line of equal or constant pressure.

Same as windsock.

An up slope wind due to local surface heating. Opposite of katabatic wind.

An instrument used to reveal but not necessarily measure the presence of an electrical quantity. It is used to display the output of a sensing element after suitable amplification and modification. Sometimes called display.

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.

The temperature at which the liquid and solid forms of a substance may exist in equilibrium at a given pressure (usually one standard atmosphere). The true freezing point of water is known as the ice point.

Upwarddirected solar radiation, reflected by the earth's surface and the atmosphere.

In nautical terminology, a contraction for "weather glass" (a mercury barometer).

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

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.