Safety precautions and warnings
3.4
3.4
Wind speeds
Wind speed averaged over 10 minutes at a
height of 10 m
Above flat ground
Characteristics
Wind
Force
m/s
Wind type
Calm
Calm, smoke rises vertically or nearly
0
0.0 - 0.2
vertically
Slight breeze
Wind direction recognisable from
smoke plumes, the wind begins to be
1
0.3 - 1.5
noticeable on the face; leaves begin to
2
1.6 - 3.3
rustle and weather vanes can start to
move.
Moderate wind
Leaves and twigs in continuous move-
3
3.4 - 5.4
ment, small branches begin to move.
Dust and paper begin to move over the
4
5.5 - 7.9
ground.
Fairly strong wind
Small leaved branches make swaying
5
8.0 - 10.7
movements; crested waves form on
lakes and canals.
Strong wind
Large branches move; you can hear
the wind whistling in telephone wires;
6
10.8 - 13.8
umbrellas can only be held with diffi-
culty.
Severe wind
Entire trees move; the wind causes
7
13.9 - 17.1
difficulty when you walk into it.
8
17.2 - 20.7
Stormy wind
Twigs break off, walking is difficult.
Storm
Causes superficial damage to buildings
9
20.8 - 24.4
(chimney pots, roof-tiles, and TV
antennae are blown off).
Severe storm
Uprooted trees; considerable damage
10
24.5 - 28.4
to buildings etc. (occurs infrequently
on land).
Very severe storm
Causes extensive damage (occurs very
11
28.5 - 32.6
infre quently on land).
12
> 32.6
Hurricane
Operator's Manual GB
29
