Beaufort scale

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Beaufort scale

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.


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

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Beaufort Scale


a conventional scale for the visual estimation of the force (speed) of the wind, expressed in numbers, by its action on surface objects or wave agitation on the surface of the sea. It was devised by the English admiral F. Beaufort in 1806; at first it was used only by Beaufort himself. In 1874 it was accepted by the Permanent Committee of the First Meteorological Congress for general international

Table 1. Wind force at the earth’s surface according to the Beaufort scale (at a standard altitude of 10 m above an open, even surface)
Beaufort no.Descriptive term tor wind torceWind speed (m/sec)Action of wind
on landon the surface of the sea
0Calm0–0.2Calm. Smoke rises vertically.Smooth, calm.
1Quiet0.3–1.5Direction of wind shown by smoke drift but not by wind vanes.Ripples, no spray on the crests.
2Light breeze1.6–3.3Wind felt on face, leaves rustle, wind vane moved by wind.Short waves. The crests do not break and are glassy.
3Gentle breeze3.4–5.4Leaves and small twigs in constant motion, wind extends light flag.Short, well defined waves. Crests break, form glassy spray; occasionally whitecaps form.
4Moderate breeze5.5–7.9Wind raises dust and paper, moves small b-anches.Long waves, whitecaps are frequent.
5Fresh breeze8.0–10.7Small trees sway, small waves crest on water.Long, but not very large waves, whitecaps are everywhere (spray sometimes forms).
6Strong breeze10.8–13.8Large branches in constant motion, wires on telephone poles hurr.Large waves form. Large number of foamy crests (spray is likely).
7Moderate gale13.9–17.1Large trees sway, walking against wind difficult.Waves become large, crests break, foam forms in band on the windward side.
8Fresh gale17.2–20.7Twigs break off trees, walking against the wind very difficult.Moderately high, long waves. Spray is blown from the crests. Bands of foam lie in strips in the direction of the wind.
9Strong gale20.8–24.4Minor damage; the wind blows off chimneys and tile.High waves. Foam lies on the windward side in wide, solid bands. Wave crests begin to break and form spray which decreases visibility.
10Whole gale24.5–28.4Considerable damage to buildings, trees are uprooted. Rare on dry land.Very high waves with long crests which are bent down. Foam is blown by the wind in large clumps of thick, white stripes. The surface of the sea is white with foam. The noise of the waves sounds like blows. Visibility is poor.
11Storm28.5–32.6Widespread damage. Seldom observed on dry land.Extremely high waves. Small and medium size vessels disappear from view from time to time. The sea is covered by long, white flecks of foam, collecting on the windward side. The edges of waves are covered with foam. Visibility is poor.
12Hurricane32.7 and higherWidespread damage. Seldom observed on dry land.The air is filled with foam and spray. The sea is covered with bands of foam. Very poor visibility.

synoptic usage. In subsequent years the Beaufort scale was changed and improved. In 1963, the International Meteorological Organization accepted the Beaufort scale given in Table 1 for general practice. The Beaufort scale is widely used in navigation.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

Beaufort scale

A set of descriptive terms of wind strength, evolved according to the effect of wind upon sailing craft and sea disturbance. Captain Beaufort devised the scale in 1806. The scale is depicted in the illustration. (See page 102)
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

Beaufort scale

Meteorol an international scale of wind velocities ranging for practical purposes from 0 (calm) to 12 (hurricane force). In the US an extension of the scale, from 13 to 17 for winds over 64 knots, is used
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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