Many people work out of doors in winter and with more involvement in
winter sports, the wind chill index has become important in planning
outdoor activities in extreme cold temperatures.
Wind chill index (also called wind-chilled factor.) The cooling effect
of any combination of temperature and wind, expressed as the loss of body
heat in kilograms per hour per square meter of skin surface.
The term "wind chill" was coined by Antarctic Explorer Paul A. Siple in
1939. During the 1940s Paul Siple and Charles F. Passel conducted
experiments with the temperature and wind speed to develope the wind
chill formula.
Artic explorers and militay experts have developed what is called the
wind-chill index which shows the combined effects of the wind and the temperature
on exposed skin.
The wind chill index is only an approximation because how you actually
feel will also depend on other variables such as the type of clothing
worn, amount of exposed flesh, the amount of radiation, and your
physical condition at the time. These temperatures and the heat loss
valures are applicable to man and not inaniamte objects.
It has been shown through experiments that human flesh will freeze at a
temperature of 18 degs. F., and a wind speed of 22 mph in one hour, or
at -22 degs. F., with a 22 mph wind in one minute.
The following chart can be used to determine the wind chill effect.
The numbers in the left margin are the air temperature degrees F. The numbers
across the top are are wind speed in mph.
To find what the wind chill effect is with a temperature of 20 degs. F.
and a wind speed of 20 mph.
1. Find the wind speed of 20 mph at the top of the chart.
2. Next, located 20 degs. F. at the left margin.
3. Find where these meet on the chart. This would be at 4 degs. F.
4. This is the wind chill effect. The combination of wind speed and
temperature.