Beaufort Wind Scales
|
Beaufort |
Wind Speed |
Wave |
WMO* |
Effects observed on the sea |
Effects observed on land |
||
|
knots |
mph |
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|
0 |
under 1 |
under 1 |
- |
Calm |
Sea is like a mirror |
Calm. Smoke rises vertically | |
|
1 |
1 - 3 |
1 - 3 |
0.25 |
Light air |
Ripples with appearance of scales; no foam crests |
Smoke Drift indicates wind direction and wind vanes cease moving | |
|
2 |
4 - 6 |
4 - 7 |
0.5 - 1 |
Light breeze |
Small wavelets; crests of glassy appearance, not breaking |
Wind felt on exposed skin. Leaves rustle and wind vanes begin to move. | |
|
3 |
7 - 10 |
8 - 12 |
2 - 3 |
Gentle breeze |
Large wavelets; crests begin to break; scattered whitecaps |
Leaves and small twigs constantly moving, light flags extended. | |
|
4 |
11-16 |
13-18 |
3½ - 5 |
Moderate breeze |
Small waves, becoming longer; numerous whitecaps |
Dust and loose paper raised. Small branches begin to move. | |
|
5 |
17-21 |
19-24 |
6 - 8 |
Fresh breeze |
Moderate waves, taking longer form; many whitecaps; some spray |
Branches of a moderate size move. Small trees in leaf begin to sway. | |
|
6 |
22-27 |
25-31 |
9½-13 |
Strong breeze |
Larger waves forming; whitecaps everywhere; more spray |
Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over. | |
|
7 |
28-33 |
32-38 |
13½-19 |
Near gale |
Sea heaps up; white foam from breaking waves begins to be blown in streaks |
Whole trees in motion. Effort needed to walk against the wind. | |
|
8 |
34-40 |
39-46 |
18-25 |
Gale |
Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks |
Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded. | |
|
9 |
41-47 |
47-54 |
23-32 |
Strong gale |
High waves; sea begins to roll; dense streaks of foam; spray may begin to reduce visibility |
Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. | |
|
10 |
48-55 |
55-63 |
29-41 |
Storm |
Very high waves with overhanging crests; sea takes white appearance as foam is blown in very dense streaks; rolling is heavy and visibility is reduced |
Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs. | |
|
11 |
56-63 |
64-72 |
37-52 |
Violent storm |
Exceptionally high waves; sea covered with white foam patches; visibility further reduced |
Widespread damage to vegetation. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely. | |
|
12 |
64 and over |
73 and over |
45 and over |
Hurricane |
Air filled with foam; sea completely white with driving spray; visibility greatly reduced |
Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about. | |
|
* World Meteorological Organization |
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