The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

A thermometer with a muslin-covered bulb which is moistened. used to measure wet-bulb temperature.

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.

A curve showing the variation of temperature with height in the free air. See lapse rate.

A conductor or system of conductors for radiating and/or receiving radio energy. Also called aerial.

An instrument for measuring differences of electric potential.

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

A temperature telemeter.

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

A cup anemometer with its shaft mechanically coupled to a magneto.

A motorlike device containing a rotor and a stator and capable of converting an angular position into an electrical signal, or an electrical signal into an angular position. When several synchros are correctly connected, all of the rotors will align thems ...

The difference between temperature measurements taken at two significant levels above the ground. Temperatures at 10 and 40 meters are commonly used.

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

The wind speed and direction at various levels in the atmosphere above the level reached by surface weather observations.

See radar theodolite, radio direction-finder.