wind vane

weather vane

weather vane or wind vane, instrument used to indicate wind direction. It consists of an asymmetrically shaped object, e.g., an arrow or a rooster, mounted at its center of gravity so it can move freely about a vertical axis. Regardless of the design, the portion of the object with greater surface area (usually the tail) offers greater resistance to the wind and thus positions the vane so that the forward part points in the direction from which the wind is blowing. The compass direction of the wind may then be determined by reference to an attached compass rose; alternatively, the orientation of the vane may be relayed to a remote calibrated dial. The wind vane must be mounted at a distance from the nearest obstacle equal to at least twice the height of the obstacle above the vane if the observed wind direction is to be representative of meteorologically significant wind patterns; for this reason, the vane is often mounted on a pole or tower that is in turn mounted on the roof of a tall building.

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wind vane

[′win ‚vān]

(engineering)

An instrument used to indicate wind direction, consisting basically of an asymmetrically shaped object mounted at its center of gravity about a vertical axis; the end which offers the greater resistance to the motion of air moves to the downwind position; the direction of the wind is determined by reference to an attached oriented compass rose.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

wind vane

A device to indicate wind direction. A wind vane always points into the wind. It works on the principle of weathercocking. See weather vane.

An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved