United Kingdom forecast model. (Available via AccuWeather.com Professional.)

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

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 ...

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

Forecasting weather by the use of numerical models, run on high speed computers. Most of the NWP for the National Weather Service is done at the National Centers for Environmental Prediction (NCEP).

A general term for instruments designed to measure the speed or force of the wind.

The upward force produced by the gas in a balloon. It is equal to the free lift plus the weight of the balloon and the attached equipment.

The play or loose motion in an instrument due to the clearance existing between mechanically contacting parts.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

A colorless and odorless gaseous element. The lightest and apparently the most abundant chemical element in the universe. However, it is found only in trace quantities in the observable portion of our atmosphere, only about 0.00005 percent by volume of dr ...

A sunshine recorder of the type in which the time scale is supplied by the motion of the sun. It consists of two opaque metal semi-cylinders mounted with their curved surfaces facing each other. Each of the semi-cylinders has a short narrow slit in its fl ...

Any horizontal wind velocity tangent to the contour line of a constant pressure surface (or to the isobar of a geopotential surface) at the point in question.

A captive balloon used to maintain meteorological equipment aloft at approximately a constant height. The kytoon is streamlined and combines the aerodynamic properties of a balloon and a kite.

A rainbow seen in the spray of the ocean. It is optically the same phenomenon as the ordinary rainbow.

Wind with a speed between 34 and 40 knots (39 and 46 mph); Beaufort scale number 8.

The record made by a hygrograph.

See hook gauge.