# What is wind chill a function of?

When the weather report includes a wind chill, was that value experimentally determined by sampling the conditions on the day of the report? Or was it calculated from other data?

If so, what do you need to know to calculate (a good approximation of) the wind chill? Obviously wind speed and temperature, since I assume wind chill gets worse the colder the air is. What else is it a function of?

• srh.noaa.gov/ohx/?n=safety-winter-windchill gives both the formula and an explanation for how it was derived. Wind chill is effectively convection cooling. – barrycarter Jan 23 '16 at 16:08
• Wind chill is =sort= of forced convection, but not really since you can't be cooled below the actual wind temperature. That is, "Wind chill of -20" doesn't mean the forced convection of the causes you to become -20 if the dry bulb temperature is -10. It answers the question "If there were no wind, how cold would it have to be in order for you to feel as cold (have the same rate of heat loss ...)." Think of it as the "equivalent temperature without forced convection". That's the confusing point -- forced convection doesn't actually CAUSE the temperature given. So, not actually about convection. – Julie in Austin Feb 21 at 22:52