Heat, as does anything else, wants to equalize. Nature generally abhorrs vacuums, and tries to fill them. Therefore, things with less heat than their surroundings take heat, and warm things give up heat. You are warm, a can of ale is cold, so the ale gets heat from you. You feel cold. If you were holding a cup of hot coffee, the coffee would give up heat to you, making you warm.
Windchill is a mathematical function of the current temperature and windspeed. It gives a more accurate estimation of how cold it ‘feels’ out than would a straight temperature reading. So if the windchill is -20, it feels 20 degrees below zero outside factoring in the windchill.
From this site ( http://www.nws.noaa.gov/pa/secnews/tip/web-faq.htm#windchill ) we get the formulas:
In US Standard (Fahrenheit/mph):
T(wc) = 0.0817(3.71V[sup]0.5[/sup] + 5.81 -0.25V)(T-91.4) + 91.4
T(wc) is the wind chill, V is the wind speed in statute miles per hour and T is the temperature in degrees Fahrenheit. The formula for windchill, using the Celsius scale is:
T(wc) = 0.045(5.27V[sup]0.5[/sup] + 10.45 - 0.28V)(T - 33) + 33
Again, T(wc) is the wind chill, V is the wind speed in Kilometers per hour, and T is Degrees Celsius.