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Marine Beaufort Scale
The Beaufort Scale was
originally developed in 1805 by Sir Francis Beaufort as a system for
estimating wind strengths without the use of instruments. It is
currently still in use for this same purpose as well as to tie together
various components of weather (wind strength, sea state, observable
effects) into a unified picture.
|
Force |
Speed |
Marine Conditions |
|
knots |
mph |
| 0
|
<1
|
<1
|
Calm, sea
like a mirror. |
| 1
|
1-3
|
1-3
|
Light air,
ripples only. |
| 2
|
4-6
|
4-7
|
Light
breeze, small wavelets (0.2m). Crests have a glassy appearance.
|
| 3
|
7-10
|
8-12
|
Gentle
breeze, large wavelets (0.6m), crests begin to break. |
| 4
|
11-16
|
13-18
|
Moderate
breeze, small waves (1m), some white horses. |
| 5
|
17-21
|
19-24
|
Fresh
breeze, moderate waves (1.8m), many white horses. |
| 6
|
22-27
|
25-31
|
Strong
breeze, large waves (3m), probably some spray. |
| 7
|
28-33
|
32-38
|
Near gale,
mounting sea (4m) with foam blown in streaks downwind. |
| 8
|
34-40
|
39-46
|
Gale,
moderately high waves (5.5m), crests break into spindrift.
|
| 9
|
41-47
|
47-54
|
Strong
gale, high waves (7m), dense foam, visibility affected. |
| 10
|
48-55
|
55-63
|
Storm,
very high waves (9m), heavy sea roll, visibility impaired. Surface
generally white. |
| 11
|
56-63
|
64-73
|
Violent
storm, exceptionally high waves (11m), visibility poor. |
| 12
|
64+
|
74+
|
Hurricane,
14m waves, air filled with foam and spray, visibility bad.
|
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