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Page 24
5.5 - 7.9 m/s
5
Fresh breeze
29 - 38 km/h
Branches of a
moderate size move.
Small trees in leaf
begin to sway.
18 - 24 mph
17 - 21 knot
8.0 - 10.7 m/s
6
Strong breeze
39 - 49 km/h
Large branches in
motion. Whistling
heard in overhead
wires. Umbrella use
becomes difficult.
Empty plastic bins tip
over.
25 - 30 mph
22 - 27 knot
10.8 - 13.8 m/s
7
High wind
50 - 61 km/h
Whole trees in motion.
Effort needed to walk
against the wind.
31 - 38 mph
28 - 33 knot
13.9 - 17.1 m/s
8
Gale
62 - 74 km/h
Some twigs broken
from trees.
Cars veer on road.
Progress on foot is
seriously impeded
39 - 46 mph
34 - 40 knot
17.2 - 20.7 m/s
9
Strong gale
75 - 88 km/h
Some branches break
off trees, and some
small trees blow over.
Construction
/temporary signs and
barricades blow over.
47 - 54 mph
41 - 47 knot
20.8 - 24.4 m/s
10
Storm
89 - 102 km/h
Trees are broken off or
uprooted, structural
damage likely.
55 - 63 mph
48 - 55 knot
24.5 - 28.4 m/s
11
Violent storm
103 - 117 km/h
Widespread vegetation
and structural damage
likely.
64 - 73 mph
56 - 63 knot
28.5 - 32.6 m/s
12
Hurricane force
≥ 118 km/h
Severe widespread
damage to vegetation
and structures. Debris
and unsecured objects
are hurled about.
≥ 74 mph
≥ 64 knot
≥ 32.7m/s
Figure 25
5.12.3
Wind Chill
Wind Chill is the perceived decrease in air temperature felt by the body on exposed skin due to the
flow of air, and is calculated based on temperature and wind speed.
Wind chill numbers are always lower than the air temperature for values where the formula is valid.