Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

An elongated area of relatively high pressure. Usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow. The opposite of a trough.

A colloquial term in western Australia for a squall, associated with thunder, on the northwest coast in summer.

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 ...

Erasable Programmable Read Only Memory. Programable read-only memory which can be erased, usually by ultraviolet light, and re-programmed.

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

The distance or length of flow of the air past a point during a given interval of time.

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

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

The record or trace made by a microbarograph.

Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.

Infrared radiation emitted by or being propagated through the atmosphere.

The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface. This result of infrared (long-wave) absorption and reemission by the atmosphere is the principal factor in the greenhouse effect.

An instrument which determines the black-body temperature of a substance by measuring its thermal radiation.

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

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

The record obtained from a bolometer.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

A wave resulting from the action of wind on a water surface.