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Land 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 |
Land
Conditions |
|
knots |
mph |
| 0 |
<1
|
<1
|
Calm, smoke rises vertically
|
| 1 |
1-3 |
1-3 |
Light air, direction of wind shown by
smoke drift only |
| 2 |
4-6 |
4-7 |
Light breeze, wind felt on face, leaves
rustle, vanes moved by wind |
| 3 |
7-10 |
8-12 |
Gentle breeze, leaves and small twigs in
constant motion, wind extends light flag |
| 4 |
11-16
|
13-18
|
Moderate breeze, raises dust, loose
paper, small branches move |
| 5 |
17-21
|
19-24
|
Fresh breeze, small trees in leaf begin
to sway |
| 6 |
22-27
|
25-31
|
Strong breeze, large branches in motion,
umbrellas used with difficulty |
| 7 |
28-33
|
32-38
|
Near gale, whole trees in motion,
inconvenience felt walking against the wind |
| 8 |
34-40
|
39-46
|
Gale, breaks twigs off trees, impedes
progress |
| 9 |
41-47
|
47-54
|
Strong gale, slight structural damage
occurs |
| 10 |
48-55
|
55-63
|
Storm, trees uprooted, considerable
damage occurs |
| 11 |
56-63
|
64-73
|
Violent storm, widespread damage
|
| 12 |
64+ |
74+ |
Hurricane, extreme destruction
|
|
|
|
