Weather and Climate: Terms and Concepts

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Beaufort Scale

The Oxford Companion to Ships and the Sea | 2006 | Copyright

Beaufort Scale, the internationally recognized scale for wind and weather which was drawn up by Sir Francis Beaufort (1774–1857), a British rear admiral who served as Hydrographer of the Navy from 1829 to 1855. See illus. opposite.

Beaufort ScaleUsed to indicate the force of the wind.

Force on Beaufort Scale	Nautical miles per hr.	Description	Height of sea in ft	Deep sea criteria
0	0–1	Calm	—	Flat calm, mirror smooth
1	1–3	Light Airs	¼	Small wavelets, no crests
2	4–6	Light Breeze	½	Small wavelets, crests glassy but do not break
3	7–10	Light Breeze	2	Large wavelets, crests begin to break
4	11–16	Moderate Breeze	3½	Small waves, becoming longer, crests break frequently
5	17–21	Fresh Breeze	6	Moderate waves, longer, breaking crests
6	22–27	Strong Breeze	9½	Large waves forming, crests break more frequently
7	28–33	Strong Wind	13½	Large waves, streaky foam
8	34–40	Near Gale	18	High waves of increasing length, crests form spindrift
9	41–47	Strong Gale	23	High waves, dense streaks of foam, crests roll over
10	48–55	Storm	29	Very high waves, long overhanging crests. Surface of sea white with foam
11	56–65	Violent Storm	37	Exceptionally high waves, sea completely covered with foam
12	above 65	Hurricane	—	The air filled with spray and visibility seriously affected

Beaufort scale

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

Beaufort scale a scale of wind velocity devised (c.1805) by Admiral Sir Francis Beaufort of the British navy. An adaptation of Beaufort's scale is used by the U.S. National Weather Service; it employs a scale from 0 to 12, representing calm, light air, light breeze, gentle breeze, moderate breeze, fresh breeze, strong breeze, moderate gale, fresh gale, strong gale, whole gale, storm, hurricane. Zero (calm) is a wind velocity of less than 1 mi (1.6 km) per hr, and 12 (hurricane) represents a velocity of more than 74 mi (119 km) per hr.

Beaufort's original scale was later correlated to wind speed in two different ways. The U.S. and British scale is for winds measured at a 36-ft elevation, while the international scale requires only a 20-ft elevation. The Beaufort scale is the oldest method of judging wind force. Separate scales for tornadoes and hurricanes did not come until the 1970s. The Fujita scale for tornadoes was proposed in 1971 by Tetsuya (Ted) Fujita; in 2007 the Enhanced Fujita scale, incorporating improved knowledge of wind destruction, as was adopted. Soon after the development of the Fujita scale the Saffir-Simpson scale for hurricanes was formulated by Herbert Saffir and Robert Simpson.

Bibliography: See A. Shaw, Beaufort Wind Scale (1995).

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"Beaufort scale." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>.

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Beaufort scale

The Oxford Pocket Dictionary of Current English | 2009 | Copyright

Beau·fort scale / ˈbōfərt/ a scale of wind speed based on a visual estimation of the wind's effects, ranging from force 0 (less than 1 knot or 1 kph, “calm”) to force 12 (64 knots or 118 kph and above, “hurricane”).

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"Beaufort scale." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 25 May. 2012 <http://www.encyclopedia.com>.

"Beaufort scale." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 25, 2012). http://www.encyclopedia.com/doc/1O999-beaufortscale.html

"Beaufort scale." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 25, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-beaufortscale.html

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