Thermometer for measuring the temperature in the soil at different depths.

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 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 ...

See radiation shield.

Name sometimes used in place of pyranometer as a generic term.

An element that can control current without moving parts, heated filaments, or vacuum gaps.

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...

A thermometer based upon the principle that the velocity of a sound wave is a function of the temperature of the medium through which it passes. Sonic thermometers possess very short time-constants and eliminate radiation error.

Same as an upper air observation, but commonly used to refer to a single complete radiosonde observation.

The algebraic difference between the upper and lower limits of the measuring range of an instrument, i.e. a thermometer with a range of -35 to 50

In a system of moist air, the dimensionless ratio of the mass of water vapor to the total mass of the system.

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.

Solar radiation of selected wavelengths.

An instrument for taking photographs of an image of the sun in monochromatic light.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

An instrument which measures the spectral distribution of the intensity of direct solar radiation.

A liquid-in-glass thermometer which uses an organic substance such as alcohol as the thermometer liquid. This type of thermometer has a low freezing point and a high coefficient of expansion. It is less accurate, however, than a mercury thermometer.

A type of wind vane having a split or V-shaped tail. The apex orients itself to the direction of the wind.

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.