butterflies, clouds, and wind

[Michael Gochfeld]

ON sunny days the ground temperature is indeed warmer than the air 
temperature, but there is only a narrow band of this warmer microclimate 
(often less than 15 cm), which results from sunshine reflected off the 
ground surface.  It cools very quickly when a cloud passes, casting a 
shadow.  It also varies depending on a lot of factors (air temperature, 
angle of sun, nature of substrate, nature of ground cover etc). 

I used to make a lot of these measurements when I was studying the 
thermoregulatory behavior of ground-nesting birds. 

Mike Gochfeld