The wind chill tables are based on the rate of heat loss from a one liter cylinder of water at 33 C (91.4 F). The tables are for this notional cylinder at various ambient temperatures and velocities. WCI = (33 - t )*(10.45 - V + 10*sqrt(V)) kcal/m2/h where t = ambient temperature in C V = wind velocity in m/sec WCI = the "wind chill index" T = -0.04544*WCI + 33 where T = the equivalent wind chill temperature Conversion to degress F and miles per hour is left as an exercise for the reader. :)