The Beaufort Wind Scale |
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Beaufort Wind Scale |
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| Beaufort Number or Force |
Wind Speed |
Description | Effects Land / Sea | ||
| mph | km/hr | knots | |||
| 0 | <1 | <1 | <1 | Calm | Still, calm air, smoke will rise vertically. Water is mirror-like. |
| 1 | 1-3 mph |
1-5 kph |
1-3 knots |
Light Air | Rising smoke drifts, wind vane is inactive. Small ripples appear on water surface. |
| 2 | 4-7 mph |
6-11 kph |
4-6 knots |
Light Breeze | Leaves rustle, can feel wind on your face, wind
vanes begin to move. Small wavelets develop, crests are glassy. |
| 3 | 8-12 mph |
12-19 kph |
7-10 knots |
Gentle Breeze | Leaves and small twigs move, light weight flags
extend. Large wavelets, crests start to break, some whitecaps. |
| 4 | 13-18 mph |
20-28 kph |
11-16 knots |
Moderate Breeze | Small branches move, raises dust, leaves and
paper. Small waves develop, becoming longer, whitecaps. |
| 5 | 19-24 mph |
29-38 kph |
17-21 knots |
Fresh Breeze | Small trees sway. White crested wavelets (whitecaps) form, some spray. |
| 6 | 25-31 mph |
39-49 kph |
22-27 knots |
Strong Breeze | Large tree branches move, telephone wires
begin to "whistle", umbrellas are difficult to keep under control. Larger waves form, whitecaps prevalent, spray. |
| 7 | 32-38 mph |
50-61 kph |
28-33 knots |
Moderate or Near Gale | Large trees sway, becoming difficult to walk. Larger waves develop, white foam from breaking waves begins to be blown. |
| 8 | 39-46 mph |
62-74 kph |
34-40 knots |
Gale or Fresh Gale | Twigs and small branches are broken from trees,
walking is difficult. Moderately large waves with blown foam. |
| 9 | 47-54 mph |
75-88 kph |
41-47 knots |
Strong Gale | Slight damage occurs to buildings, shingles are
blown off of roofs. High waves (6 meters), rolling seas, dense foam, Blowing spray reduces visibility. |
| 10 | 55-63 mph |
89-102 kph |
48-55 knots |
Whole Gale or Storm | Trees are broken or uprooted, building damage
is considerable. Large waves (6-9 meters), overhanging crests, sea becomes white with foam, heavy rolling, reduced visibility. |
| 11 | 64-72 mph |
103-117 kph |
56-63 knots |
Violent Storm | Extensive widespread damage. Large waves (9-14 meters), white foam, visibility further reduced. |
| 12 | 73+ mph |
118+ kph |
64+ knots |
Hurricane | Extreme destruction, devastation. Large waves over 14 meters, air filled with foam, sea white with foam and driving spray, little visibility. |
One of the first scales to estimate wind speeds and the effects was created by Britain's
Admiral Sir Francis Beaufort (1774-1857). He developed the scale
in 1805 to help sailors estimate the winds via visual observations. The scale starts
with 0 and goes to a force of 12. The Beaufort scale is still used
today to estimate wind strengths. |
Type a value in one box and click in any other box to see the results