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