The Hungarian observers Attila Kovács and György Répás witnessed an unusual kind of refraction. The temperatures in the exhausts of smokestacks differ widely within a small space, which causes very bizarre distortions of the sun.
Attila reports that such strangely distorted solar disks can be seen almost every day in the exhausts of smokestacks. So it is worth while trying it by yourself to get a live impressions of physics.
Attila Kovács at the hospital of Eger, November 11, 2014:
György Répás, smokestack in Budapest, March 29, 2014: