The accompanying explanation is OK, but I'd quibble with some statements there. A page of pictures offered commercially. This is a gif animation of a sunset sequence. The mock mirage shows up very nicely in the 3rd frame of the series, and there is the corresponding green flash in the 9th frame. The animation gives a good feel for the progression of forms in this typical mock-mirage sunset.
Associated pages show several fine rainbows and a beautiful example of anticrepuscular rays.
A couple of sunsets with strong ducting features are shown down near the end of this page, one with a small green flash in the upper part. This is one of the less-common forms that are not yet well understood. A small blue flash of the mock-mirage type. Green Flash Photo. A small inferior-mirage flash, with a slightly yellower center.