|
mph
|
Description
|
Visible
Condition |
|
0
|
Calm
|
smoke rises
vertically
|
|
1 - 4
|
Light air
|
direction
of wind shown by smoke but not by wind vanes
|
|
4 - 7
|
Light breeze
|
wind felt
on face; leaves rustle; ordinary wind vane moved by wind
|
|
8 - 12
|
Gentle breeze
|
leaves and
small twigs in constant motion; wind extends light flag
|
|
13 - 18
|
Moderate breeze
|
raises dust
and loose paper; small branches are moved
|
|
19 - 24
|
Fresh breeze
|
small trees
in leaf begin to sway; crested wavelets form on inland water
|
|
25 - 31
|
Strong breeze
|
large branches
in motion; telephone wires whistle; umbrellas used with difficulty
|
|
32 - 38
|
Moderate gale
|
whole trees
in motion; inconvenience in walking against wind
|
|
39 - 46
|
Fresh gale
|
breaks twigs
off trees; generally impedes progress
|
|
47 - 54
|
Strong gale
|
slight structural
damage occurs; chimney pots and slates removed
|
|
55 - 63
|
Whole gale
|
trees uprooted;
considerable structural damage occurs
|
|
64 - 72
|
Storm
|
very rarely
experienced; accompanied by widespread damage
|
|
73+
|
Hurricane
|
devastation
occurs
|