ENCYCLOPEDIC ENTRY
ENCYCLOPEDIC ENTRY
Beaufort Scale
Beaufort Scale
The Beaufort scale measures wind strength.
Grades
9 - 12
Subjects
Health, Earth Science, Meteorology
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The Beaufort scale, officially known as the Beaufort wind force scale, is a descriptive table. It depicts the force of wind by a series of numbers, typically from 0 to 12. The Beaufort scale goes all the way to 17, but the last five numbers only apply to tropical typhoons. These numbers are only used in the areas around China and Taiwan.
The scale is named for Sir Francis Beaufort of the British Royal Navy. In 1805, he devised a method of describing wind force according to procedures for setting sails on a warship.
The Beaufort scale is useful for estimating wind power without wind instruments.
0: Calm and still winds. Smoke rises vertically.
1. Light winds at 1-5 kph (1-3 mph). Smoke drift shows wind direction.
2. Light breeze at 6-11 kph (4-7 mph). Wind can be felt on face; flags ripple.
3. Gentle breeze at 12-19 kph (8-12 mph). Flags wave.
4. Gentle breeze at 20-28 kph (13-18 mph). Paper and leaves scatter.
5. Fresh breeze at 29-38 kph (19-24 mph). Small trees sway; whitecaps form on waves.
6. Strong breeze at 39-49 kph (25-31 mph). Umbrellas are hard to use; large branches on trees move.
7. Moderate gale at 50-61 kph (32-38 mph). Trees sway; walking in the wind is difficult.
8. Fresh gale at 62-74 kph (39-46 mph). Twigs and branches break off trees.
9. Strong gale at 75-88 kph (47-54 mph). Roof tiles blow off buildings.
10. Whole gale at 89-102 kph (55-63 mph). Trees are uprooted.
11. Storm at 103-118 kph (64-73 mph). Widespread damage to vegetation and buildings; there's nearly no visibility at sea.
12. Hurricane at 119-220 kph (74-136 mph). A Category 1 hurricane or a Category 1 tornado. There's Widespread destruction.
Fast Fact
Hurricane Warning
Hurricane warnings are issued when winds reach 12 on the Beaufort scale. But actual hurricane categories are determined by different factors. A 12 on the Beaufort scale is a Category 1 (lowest level) hurricane, but a 13 on the Beaufort scale is not a Category 2; it's actually much, much stronger.
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Last Updated
October 19, 2023
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