An instrument which automatically records the voltage applied to it, as a function of time.

The difference between downward and upward (total) radiation; net flux of all radiation.

A type of pressure-plate anemometer in which the plate, restrained by a stiff spring, is held perpendicular to the wind. The wind-activated motion of the plate is measured electrically. The natural frequency of this system can be made high enough so that ...

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

Nested Grid Model generated every 12 hours by NCEP.

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

Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system. Compare to adiabatic process.

Name sometimes given to a transmissometer.

See bimetallic thermometer.

A polariscope consisting of a specially constructed double plate polarizer and a tourmaline plate analyzer. Polarized light passing through the instrument is indicated by the presence of parallel colored fringes, while unpolarized light results in a unifo ...

Same as constant-level balloon.

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

Any one of six gases, helium, neon, argon, krypton, xenon, and radon, all of whose shells of planetary electrons contain stable numbers of electrons such that the atoms are chemically inactive.

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

pattern barometer-Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.

A local variation of the wind vector or any of its components in a given direction.

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 ...

A measure of the degree to which the weather or climate of a region is favorable to the process of evaporation. Usually considered to be the rate of evaporation. under existing atmospheric conditions, from a surface of water which is chemically pure and h ...

One of several constant-pressure levels in the atmosphere for which a complete evaluation of data derived from upper air observations is required.