Wind-chill or windchill, (popularly wind chill factor) is the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air.
Wind chill numbers are always lower than the air temperature for values where the formula is valid. When the apparent temperature is higher than the air temperature, the heat index is used instead.
A measure of the cooling effect of
wind. Wind increases the rate at which a body loses heat, so the air
on a windy day feels cooler than the temperature indicated by a
thermometer. This heat loss can be calculated for various
combinations of wind speed and air temperature and then converted to
a wind chill equivalent temperature (or wind chill factor).
Wind Chill Temperature °F = 35.74 + 0.6215T - 35.75(V0.16) + 0.4275T(V0.16)
Where T = Air Temperature (F)
V = Wind Speed (mph)
Reference Machinery's Handbook 29th edition
Wind Chill is defined for temperatures within the range -45oF
to +45oF and wind speeds 3 to 60 mph. Wind Chill temperature only
will not cause water to freeze. Water will only freeze when the waters
temperature reaches the freezing point.
Wind Reference Chart