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Beaufort Scale | ||||||||||||
The Beaufort Scale was originally developed in 1806 by Admiral Sir Francis Beaufort. The Beaufort Scale is divided into a series of speeds from 0 for calm winds to 12 for hurricanes. Each value represents a range of wind speeds with descriptions of effects on surface features |
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Beaufort Number |
Wind Speed (mph) |
Seaman's Term |
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Effects on Land |
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0 | Under 1 |
Calm |
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Calm, smoke rises vertically. |
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1 | 1 - 3 |
Light Air |
Smoke drift indicates wind direction, weather vanes do not move. |
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2 | 4 - 7 |
Light Breeze |
Wind felt on face, leaves rustle, Vanes begin to move. |
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3 | 8 -12 |
Gentle Breeze |
Leaves, small twigs in constant motion, small flags extended. |
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4 | 13 -18 |
Moderate Breeze |
Dust, leaves and loose paper move up, small branches move. |
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5 | 19 - 24 |
Fresh Breeze |
Small trees begin to sway. |
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6 | 25 - 31 |
Strong Breeze |
Large branches of trees in motion. |
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7 | 32 - 38 |
Moderate Gale |
Whole trees in motion, resistance felt in walking against wind. |
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8 | 39 - 46 |
Fresh Gale |
Twigs and small branches broken off trees. |
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9 | 47 - 54 |
Strong Gale |
Slight structural damage occurs, slates blown from roofs. |
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10 | 55 - 63 |
Whole Gale |
Tress damaged, structural damage occurs |
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11 | 64 - 72 |
Storm |
Widespread damage |
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12 | 72 or higher |
Hurricane Force |
Violent destruction. |
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