<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> 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>
when did they change the wind chill formula
when did they change the wind chill formula
November 2001
November 2001