A hygrometer in which the rotation of the hygrometric element is a function of humidity.

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 ...

A form of data transmission in which the bits of each character are sent one at a time along a single communication path. Compare to parallel data transmission.

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

A unit of power equal to one joule per second or 10' ergs per second.

Readily taking up and retaining moisture.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

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

The gravity flow of water within soil.

Same as atmometer.

See sea-water thermometer, reversing thermometer.

A pressure-operated switching device used in a radiosonde. In operation, the expansion of an aneroid capsule causes an electrical contact to scan a radiosonde commutator composed of conductors separated by insulators.

Of or pertaining to rain.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

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.

Same as windsock.

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec2. Commonly used in gravimetry.