The Beaufort Scale of Wind Force
|
BEAUFORT FORCE |
DESCRIPTIVE TERMS |
EFFECT OF WIND STRENGTH ON LAND AND SEA |
WIND SPEED IN KNOTS |
0 |
Calm |
Smoke rises vertically and the sea is glassy or mirror smooth. |
less
than 1 |
1 |
Light
Air |
Smokes moves slightly with breeze and indicates the direction of wind. |
1 -
3 |
2 |
Light
Breeze |
You can feel the wind on your face and hear the gentle movement of leaves on trees and shrubs. |
4 -
6 |
3 |
Gentle
Breeze |
Smoke will move horizontally and small branches start to sway. The wind will extend a light flag. |
7 -
10 |
4 |
Moderate
Breeze |
Loose dust or sand will move and large branches will sway. Fairly frequent wave whitecaps occur. |
11
- 16 |
5 |
Fresh
Breeze |
Surface waves form on water and small trees will sway in the wind. |
17
- 21 |
6 |
Strong
Breeze |
Trees begin to bend with the force of the wind and some spray forms on the sea surface. |
22
- 27 |
7 |
Near
Gale |
Large trees will be caused to sway by the force of the wind. |
28
- 33 |
8 |
Gale |
Twigs will break from trees and long streaks of foam appear on the sea. |
34
- 40 |
9 |
Strong
Gale |
The force of the wind will cause branches to break from trees. |
41
- 47 |
10 |
Storm |
Whole trees are uprooted and the sea takes on a foamy white appearance. |
48 - 55 |
11 |
Violent
Storm |
The force of the wind will cause considerable widespread damage. |
56
- 63 |
12 |
Hurricane |
Major structural damage will occur on land and intense storm waves will form at sea. |
64
and over |