3.2. Wind speeds
Wind speed averaged over 10 minutes at a height of 32 ft 9.7 in
Wind
Force
Above flat ground
Characteristics
mph
Wind type
0
0.0 - 0.4
Calm
Calm, smoke rises vertically or nearly
vertically
1
2
0.5 - 3.4
3.5 - 7.4
Slight breeze
Wind direction recognisable from smoke
plumes, the wind begins to be noticeable on
the face; leaves begin to rustle and weather
vanes can start to move.
3
4
7.5 - 12.0
12.1 - 18.0
Moderate wind
Leaves and twigs in continuous movement,
small branches begin to move. Dust and
paper begin to move over the ground.
5
18.1 - 24.0
Fairly strong
wind
Small leaved branches make swaying
movements; crested waves form on lakes
and canals.
6
24.1 - 31.0
Strong wind
Large branches move; you can hear the
wind whistling in telephone wires; umbrellas
can only be held with difficulty.
7
31.1 - 38.0
Severe wind
Entire trees move; the wind causes difficulty
when you walk into it.
8
38.1 - 46.0
Stormy wind
Twigs break off, walking is difficult.
9
46.1 - 55.0
Storm
Causes superficial damage to buildings
(chimney pots, roof-tiles, and TV antennae
are blown off).
10
55.1 - 64.0
Severe storm
Uprooted trees; considerable damage to
buildings etc. (occurs infrequently on land).
11
64.1 - 73.0
Very severe
storm
Causes extensive damage (occurs very infre
quently on land).
12
> 73.0
Hurricane
Safety precautions and warnings
16
HIAB J14S J24S
