Beaufort scale
Beaufort Wind Scale and Sea State Chart
Sea State
|
Beaufort Number
|
Terminology
|
Wind Speed (miles per hour)
|
Average Wave Height (feet)
|
Description
|
0
|
0
|
Calm
|
0-1
|
0
|
Sea like a mirror
|
1
|
1
|
Light air
|
1-3
|
0.005
|
Ripples with appearance of scales; no crests
|
2
|
2
|
Light breeze
|
4-7
|
0.18
|
Small wavelets; crests have glossy appearance but do not break.
|
3
|
3
|
Gentle breeze
|
8-12
|
0.19-1
|
Large wavelets, crests begin to break; foam of glossy appearance; a few white horses.
|
|
4
|
Moderate breeze
|
13-18
|
2-3
|
Small waves becoming longer form; many white horses formed; some spray
|
4
|
5
|
Fresh breeze
|
19-24
|
4-5
|
Moderate waves taking longer form; many white horses formed; some spray
|
|
6
|
Strong breeze
|
25-31
|
6-10
|
Large waves begin to form; many white crests more spray
|
|
7
|
Moderate gale
|
32-38
|
11-16
|
Sea heaps up; white foam from breaking waves begins to be blown in streaks
|
5
|
8
|
Fresh gale
|
39-46
|
17-28
|
Moderately high waves of greater length; edges of crests begin to break into spindrift; foam blown in well marked streaks spray affects visibility.
|
|
9
|
Strong gale (storm)
|
47-54
|
29-40
|
High waves; dense streaks of foam along wind direction; sea begins to roll; visibility affected
|
|
10
|
Whole gale (heavy storm)
|
55-63
|
41-59
|
Very high waves with long overhanging crests; sea takes white appearance; rolling heavy; visibility affected.
|
|
11
|
Violent storm
|
64-72
|
60-73
|
Exceptionally high waves; small and medium sized ships lost from view; crests blown into froth.
|
|
12
|
Hurricane
|
73-82
|
74-80
|
Air filled with foam and spray; sea completely white with driving spray; visibility very seriously affected.
|
|
Last modified: Tuesday, 6 December 2011, 6:41 AM