24
44.6 ˚F) to say how comfortable one feels at certain temperatures and wind speeds
whilst wearing appropriate clothing. These conditions are a temperature below
91.4␣ °F and a wind speed higher than 9.4 mph. Wind chill is defined as the cooling
effect of uncovered skin at an assumed constant 91.4 °F skin surface temperature.
The higher the wind speed is and the lower the actual temperature, the more
noticeable is the wind chill effect.
The "perceived temperature" is roughly comparable to the so-called felt tempera-
ture, which additionally takes into account the radiation effect of the sun, light re-
fection from the clouds, the light wavelength, etc.
Wind strength table
Beaufort Wind speed mph Wind speed km/h Description
0 0 - 1 0 - 0.7 Calm
1 1 - 3 0.8 - 5.4 Slight air
2 4 - 7 5.5 - 11.9 Light breeze
3 8 - 12 12.0 - 19.4 Gentle breeze
4 13 - 18 19.5 - 28.5 Moderate breeze
5 19 - 24 28.6 - 38.7 Fresh breeze
6 25 - 31 38.8 - 49.8 Strong breeze
7 32 - 38 49.9 - 61.7 Moderate gale
8 39 - 46 61.8 - 74.6 Fresh gale
9 47 - 54 74.7 - 88.9 Strong gale
10 55 - 63 89.0 - 102.,4 Whole gale
11 64 - 72 102.5 - 117.4 Storm
12 > 73 > 117.4 Hurricane
The Comfort Indicator (☺) represents the climatic conditions, for which the
following table is used (the symbol status shows the area of validity):
Temperature Humidity
20% 30% 35% 40% 45% 50% 55% 60% 65% 70%
< 64.4°F
64.4°F-67.8°F
67.9° F-71.4°F ☺☺ ☺☺
71.4°F-75.0°F ☺☺☺ ☺
75.1° F-78.6°F ☺☺☺☺
78.7°F-82.2°F
> 82.2°F