wrote:

And several Mountain Flying books mention that specifically. The
official temperature anywhere is always in the shade. Ever seen a
runway in the shade?


The runway will no doubt have a higher temperature and the air above
will be warmer than reported but how high would you need to fly to
reach the reported air temperature as measured in the shade?



An irrelevant question if you can't get there in the first place. But
if you want an answer just look at the standard lapse rate as a start.