we know from experience that we feel cooler when winds blows over us. this is the so-called chilling effect of the wind. the effect is due to the forced convection heat transfer since the heat transfer coefficient increases with increasing air velocity.
the equivalent windchill temperature in degrees fahrenheit can be determined from:
for velocities less than 6.4 km/h (3.97 mph) the above equation is not valid and the wind chill temperature is equal to the air temperature. also, this equation should not be used for velocities above 80 km/h ( 48 mph).