Wind Chill Index (Original, Vintage)

The Wind Chill Index is popularly known as the Wind Chill Factor.  It is a calculation of the perceived decrease in temperature which is experienced when wind blows across an exposed surface.  The original formula was usually calculated and distrubuted as a table for looking up the wind chill,  and the value sometimes became known as the wind chill equivalent temperature (WCET).

The Original Wind Chill calculations created a result which was just an index range and needed to be 'personally calibrated'  to be useful for each individual.  There was general guidance such as 1400, understood to be the lower temperature range in which frostbite can occur.

This equation takes as input :

`V`  -  the wind velocity (`m/s`)

`T_a`  -  the air temperature (C)       

These are used to compute the Wind Chill Index,  which is the perceived (what it really feels like) temperature.