| Description
of wind |
Specification
for use on land |
MPH |
| 0
Calm |
Calm,
smokes rises vertically |
1 |
| 1
Light Air |
Direction
of wind shown by smoke drift but not by wind vanes |
1
-
3 |
| 2
Light Breeze |
Wind
felt on face; leaves rustle; ordinary vanes moved by wind |
4
-
7 |
| 3
Gentle Breeze |
Leaves
and small twigs in constant motion; wind extends light flag |
8
-
12 |
| 4
Moderate Breeze |
Raises
dust and loose paper; small branches are moved |
13
-
18 |
| 5
Fresh Breeze |
Small
trees in leaf begin to sway; crested wavelets form on inland waters |
19
-
24 |
| 6
Strong Breeze |
Large
branches in motion; umbrellas used with difficulty |
25
-
31 |
| 7
Near Gale |
Whole
trees in motion; inconvenience felt when walking against wind |
32
-
38 |
| 8
Gale |
Breaks
twigs off trees; generally impedes progress |
39
-
46 |
| 9
Strong Gale |
Slight
structural damage occurs
(chimney pots and slates removed) |
47
-
54 |
