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Beaufort wind scale

Definition

Wind force scale expressed numerically from 1 - 12. 0. Calm. Calm, smoke rises vertically: 0 - 1 mph.1. Light air. Direction of wind shown by smoke drift but not by wind vanes: 1 - 3 mph. 2. Light breeze. Wind felt on face; leaves rustle; ordinary vane moved by wind: 4 - 7 mph. 3. Gentle breeze. Leaves and small twigs in constant motion; wind extends light flag: 8 - 12 mph. 4. Moderate breeze. Raised dust and loose paper; small branches are moved: 13 - 18 mph. 5. Fresh breeze. Small trees in leaf begin to sway; crested wavelets form on inland water: 19 - 24 mph. 6. Strong breeze. Large branches in motion; whistling heard in telegraph wires; umbrella used with difficulty: 24 - 31 mph. 7. Moderate gale. Whole trees in motion; inconvenience felt when walking against wind: 32 - 38 mph. 8. Fresh gale. Breaks twigs off trees; generally impedes progress : 39 - 46 mph. 9. Strong gale. Slight structural damage occurs; chimney pots and slats removed: 47 - 54 mph. 10.Whole gale. Seldom experienced inland; trees uprooted; considerable structural damage occurs: 55 - 63 mph. 11.Storm. Very rarely experienced, accompanied by widespread damage: 64 - 75 mph. 12. Hurricane. > 75 mph or above.

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