Beaufort scale

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Beaufort scale,

a scale of windwind,
flow of air relative to the earth's surface. A wind is named according to the point of the compass from which it blows, e.g., a wind blowing from the north is a north wind.
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 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 scaleFujita scale
or F-Scale,
scale for rating the severity of tornadoes as a measure of the damage they cause, devised in 1951 by the Japanese-American meteorologist Tetsuya (Ted) Fujita (1920–98).
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 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 scaleSaffir-Simpson scale
, standard scale for rating the severity of hurricanes as a measure of the damage they cause; it is based on observations of numerous North Atlantic Basin hurricanes.
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 for hurricanes was formulated by Herbert Saffir and Robert Simpson.


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

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.


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)

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
References in periodicals archive ?
The Beaufort Scale ranges from 0 to 12, with force 0 being 'calm' and force 12 - wind speeds of 73mph or above - a hurricane.
The Beaufort scale was developed in the early 19th Century as a system for estimating wind strengths without the use of instruments.
To put things in perspective, the amount of wind needed for the AeroCity VAWT 2 to generate electricity efficiently is classified as a 'Gentle Breeze' on the Beaufort Scale for measuring wind speed," Warner explained.
But winds measuring up to six on the Beaufort scale prevented the safety boats from accompanying them on the crossing and Sir Richard reluctantly decided they should turn back.
Inshore (distance from shore < 500 m) and offshore (distance from shore > 500 m) routes were carried out in the morning and early afternoon with Beaufort scale 2 or less, sea state 0 and visibility > 300 m.
The winds at the time of the tragedy were registering at Force 7 - up to 38mph - on the Beaufort scale.
6) allows approximating the wind speed at 7-19 km/hr, a light to gentle breeze on the Beaufort Scale (#s 2-3).
Sir Francis Beaufort - an Irish hydrographer and officer in the British Royal Navy - established the Beaufort scale for indicating wind force.
His training with the weather service included a lesson on the Beaufort Scale for measuring weather effects such as wind speed and hail size.
He winds up with a close examination of what we still need to know about the effects of wind on humans, and includes helpful information on the Beaufort scale, the Saffir-Simpson hurricane scale, the world's worst tropical cyclones, the Fujita tornado scale, wind force and wind chill.
Beaufort scale, boomtown, cistern, downtown, Fault, fill earth, firebreak, five days, ghost town, Highway, one week, Plate, Railroad, Richter scale, Theodore Roosevelt, sawdust, six days, Dennis Sullivan, William Howard Taft, three days
Contributing to the value of the text are a chart of the Beaufort Scale, a diagram of the water cycle, a map of the North Pole, and a Venn diagram depicting the intersections of myths, legends, and history.

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