We are using an equation to create a graph that determines the asphalt temperature relatively to ambient temperature, weather and day time.

check the graph in this link http://fooplot.com/plot/3x7y44pfli

The equation used is:
(((-10*1)*x)+10*1)*2((exp(-6*x)*(0.4*sin(6*x))+0.1)*(15/1.5)*sin(0.9*x))+15
change the 1 values in (((-10*1)*x)+10*1) to see the results in your graphs
Accepted values from -1 to 1