A instrument designed to study small fluctuations of some quantity. The microbarograph is an example of a recording pressure variometer.

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

A self-recording thermometer.

The part of a measuring instrument which responds directly to changes in the environment.

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

Name sometimes given to a transmissometer.

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

Precipitation from a cumuliform cloud. Characterized by the suddenness of beginning and ending, by the rapid change in intensity, and usually by a rapid change in the condition of the sky. The solid or liquid water particles are usually bigger than the co ...

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 ...

The direction toward which the wind is blowing; with the wind.

The maximum rate at which precipitation can pass through the surface into the soil, for a given soil in a given condition.

Wind with a speed between 48 and 55 knots (55 and 63 mph), Beaufort scale number 10.

A type of atmometer. It is a pan used in the measurement of the evaporation of water into the atmosphere. The NWS Class A pan is a cylindrical container 48 inches in diameter and 10 inches deep.

See radiosonde commutator.

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

A forecast of weather elements of particular interest to aviation; including ceiling, visibility, upper winds, icing, turbulence, precipitation types, and storms.

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.

A vent used with pressure sensors to reduce the effect of wind on the pressure inlet. It is normally mounted remotely and connected to the sensor using airtight tubing.

Same as atmometer.

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