The Beaufort Scale of Wind Force

Force
Speed in MPH 10m above ground
Speed in Knots 10m above ground
DESCRIPTION
SPECIFICATIONS FOR USE AT SEA
SPECIFICATIONS FOR USE On Land
0
0-1
0-1
Calm
Sea like a mirror
Calm; smoke rises vertically.

1
1-3
1-3
Light air
Ripples with the appearance of
scales are formed, but without
foam crests.
Direction of wind shown by
smoke drift, but not by wind
vanes.
2
4-7
4-6
Light Breeze
Small wavelets, still short,
but more pronounced. Crests
have a glassy appearance and
do not break.
Wind felt on face; leaves
rustle; ordinary vanes moved
by wind.
3
8-12
7-10
Gentle Breeze
Large wavelets. Crests begin
to break. Foam of glassy
appearance. Perhaps scattered
white horses.
Leaves and small twigs in
constant motion; wind extends
light flag.

4
13-18
11-16
Moderate Breeze
Small waves, becoming larger;
fairly frequent white horses.
Raises dust and loose paper;
small branches are moved.
5
19-24
17-21
Fresh Breeze
Moderate waves, taking a more
pronounced long form; many
white horses are formed.Chance of some spray.
Small trees in leaf begin to
sway; crested wavelets form on
inland waters.
6
25-31
22-27
Strong Breeze
Large waves begin to form; the
white foam crests are more
extensive everywhere.Probably some spray.
Large branches in motion;
whistling heard in telegraph
wires; umbrellas used with
difficulty.
7
32-38
28-33
Near Gale
Sea heaps up and white foam
from breaking waves begins to
be blown in streaks along the
direction of the wind.

Whole trees in motion;
inconvenience felt when walking
against the wind.
8
39-46
34-40
Gale
Moderately high waves of greater
length; edges of crests begin to
breakinto spindrift. The foam is
blown in well-marked streaks
along the direction of the wind.
Breaks twigs off trees;
generally impedes progress.
9
47-54
41-47
Severe Gale
High waves. Dense streaks of
foam along the direction of the
wind. Crests of waves begin to
topple, tumble and roll over.
Spray may affect visibility.
Slight structural damage occurs
(chimney-pots and slates removed).

10
55-63
48-55
Storm
Very high waves with long over-
hanging crests. The resulting
foam, in great patches, is blown
in dense white streaks along the
direction of the wind. On the
whole the surface of the sea
takes on a white appearance.
The 'tumbling' of the sea becomes
heavy and shock-like. Visibility
affected.
Seldom experienced inland; trees
uprooted; considerable structural
damage occurs.
11
64-75
56-63
Violent Storm
Exceptionally high waves (small
and medium-size ships might be for
a time lost to view behind the
waves). The sea is completely
covered with long white patches
of foam lying along the direction
of the wind. Everywhere the edges
of the wave crests are blown into
froth. Visibility affected.
Very rarely experienced;
accompanied by wide-spread damage.
12
Above 75
Above 64
Hurricane
The air is filled with foam and
spray. Sea completely white with
driving spray; visibility very
seriously affected.
Countryside is devastated