"Richard Riley" wrote
....
There's a chart listing ambient temperature, surface temperature and
color that composite builders take as gospel. I'm trying to get more
information about it

http://hallert.net/cozy/images/ColorCurveChart.gif

In the testing that I'm doing, these temperatures seem high. White
surfaces don't seem to be more than about 10 degrees F higher than
ambient, the chart shows a white surface on a 30 degree day at 85
degrees. Yesterday it was hot in So Ca, 90 degrees ambient - but
black surfaces were coming out at 185, not 210.

I would attribute the lower temperatures to the fact that the sun is much
lower in the sky, than at June 21, or around then.

I'll bet it was done as a worse case scenario, with the sun's rays the most
direct, and highest in the sky.
--
Jim in NC