If I remember, I will try to get some temp readings of the ground under the shade trees and the ground temps of the compost area in full sun. You got me wondering if there will be a big difference in my setup.
		
		
	 
OK, got some temp readings just for fun.
Outside temp: 79F
Gravel road, full sun: 106.7F
Green grass, full sun: 89.7F
Green grass, shaded: 71.7F
Chicken run compost, full sun: 93.7F
Chicken run compost, shade under trees: 71.7F
Note: the chicken run compost in the full sun is mainly brown, dried grass clippings at this time. Evidently, green grass in full sun is cooler than brown dried grass clippings in full sun. 
Not the full 40F difference you saw in your setup with full sun versus shade, but still a nice cooling effect under my shade trees. There was a 35F difference between the gravel road temp in full sun and the chicken run compost under the shade trees. I suspect that if I had sand in my chicken run, it would be about as hot as a gravel road.
And yes, I realized that some people might consider our current outside temp of 79F in northern Minnesota to be mid-winter for them. However, as I mentioned, when you combine 82F outside temps with 79% humidity, you feel it. Well, at least I do. I have lived in southern states and had no problem with dry heat. But the humidity here is what gets to me. You break out into a sweat just walking out to your car!