// This file implements the new windchill index which is used by U.S. and
// Canadian weather services.
//
//  See:  http://en.wikipedia.org/wiki/Wind_chill
windchill[temperature is temperature, windspeed is velocity] :=
{
   Ta = C[temperature]
   V = windspeed / (km/hr)
   Twc = C[13.12 + 0.6215 Ta - 11.37 V^0.16 + 0.3965 Ta V^0.16]
   return Twc
}

// Example:
// println[C[windchill[C[-30], 25 km/hr]]]