Here are a couple of really old pictures, not necessarily of great quality, with observations of layering.
One can perhaps guess the circumstances under which the first picture was taken, and if you look more carefully, you can see that there are people in another aircraft, maybe a few hundred feet away from us, who have a similar viewpoint.
Layering of colors is fairly typical when your aircraft is heading towards the sunset. (You can also make out the edge of the wing of our aircraft in the picture below.)
Submission for the Weekly Photo Challenge.
Splattered Brains 