<Li> v = wind velocity, m / s </Li> <Li> T = air temperature, ° C </Li> <P> In November 2001, Canada, the United States, and the United Kingdom implemented a new wind chill index developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG / TI). It is determined by iterating a model of skin temperature under various wind speeds and temperatures using standard engineering correlations of wind speed and heat transfer rate . Heat transfer was calculated for a bare face in wind, facing the wind, while walking into it at 1.4 metres per second (5.0 km / h). The model corrects the officially measured wind speed to the wind speed at face height, assuming the person is in an open field . The results of this model may be approximated, to within one degree, from the following formula: </P> <P> The standard Wind Chill formula for Environment Canada is: </P>

When did they change the wind chill formula