Shrinking Sun – Final Test (Strange Flat Bottom Sun)

July 27, 2016
Antelope Island State Park, Utah

Part 1 (similar results): https://www.youtube.com/watch?v=Wr3SHBdQAkM
Part 2 (similar results): https://www.youtube.com/watch?v=tQsdbwzSeCU

I am at a loss as to what is happening here and welcome all ideas. Simple refraction? The Sun’s a disk? The Sun is a mere reflection? The Sun’s interaction with the dome?

Here’s an official publication that shows the same phenomenon: https://www-rohan.sdsu.edu/~aty/explain/simulations/ducting/duct_intro.html