beaufort scale

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Force
Mean Speed (Knots)
Description
State of sea
Ashore
Wave height (m)
Max wave
height
0-1
Calm
Flat
Smoke rises vertically
0
0
1-3
Light air
Ripples
Smoke shows wind direction
0.1
0
4-6
Light breeze
Small wavelets, non breaking
Leaves Rustle
0.2
0.3
7-10
Gentle breeze
Large wavelets, crests breaking
Wind extends small flag, leaves in motion
0.6
1
11-16
Moderate Breeze
Fairly frequent white horses
Small branches begin to move
1
1.5
17-21
Fresh Breeze
Moderate waves, many white horses some spray
Small trees begin to sway
2
2.5
22-27
Strong breeze
Large waves, white foam crests, some spray
Large branches move
3
4
28-33
Near gale
White foam blows from crests
Branches move, difficult to walk against the wind
4
5.5
34-40
Gale
Mod high waves, foam in streaks along surface
Twigs break off trees
5.5
7.5
41-47
Strong gale
High waves, tumblong crests, dense streaks of foam, much spray
Slates, chimneys begin to be moved
7
10
48-55
Storm
Very high waves with long overhanging crests, heavy tumbling sea
Trees uprooted, structural damage to buildings
9
12.5
56-63
Violent storm
Sea completely covered with long white foam patches
Wide spread damage to buildings etc
11.5
16
64 and above
Hurricane
Air filled with foam and driving spray. Visiblilty very seriously affected
As above
14
Above 16