This one of the references:
With excel I am using this Polynomial Curve Fit:
P3 = -1.23566E-11 P2 = 1.22747E-05 P = 0.0002741 C = 0.000294794
Y=P3X3^3 + P2X^2+P *X + C
Using this adjustment is only for (Dew point + Temperature(f) ) above 100.
The input X is (Dew point + Temperature(f) -100) . The output Y is the adjusting factor for the pace needed in percentage.