Density Altitude(DA)?
http://wahiduddin.net/calc/calc_da.htm
This link will provide you with the weather conditions by zip code. Just input your zip.
http://www.weatherunderground.com/cg...st?query=36117
You will also need to get the elevation of the track you run at.
John
Thanks
Ever
http://www.modulardepot.com/density.php


