Is the visual artifact seen over the wing from different air densities, a reflection or something else? I have noticed a strange visual artifact over the wing of a Boeing yesterday. You can see two manifestations of the artifact in the pictures below.


The first shows it at the front edge of the wing. There were actually many of those, but I only managed to capture one. It looks very similar to a scratch in the window, but moving my head in front of the window didn't move the artifact. So it must have been in a distance somewhere above the wing.
The second pictures shows something similar which looked a bit like there was some kind of reflection on the wing, but the sun was on the other side of the plane, so I wasn't sure what caused it. An odd thing was that the stripe moved kind of in sync with the turbulences


Both of those things moved during the flight and were not always on the same position on the wing. Is it possible that those were caused by pressure/density differences of the air or is it just some reflection (or even something totally different)?
That is the visual effect produced by a shockwave. 

The air above the wing is accelerated and will reach Mach 1 (the speed of sound) locally.

It is usually best visible when the sun is right behind you (from the viewers perspective, so on the 3 or 9 o'clock position from the aircraft) and high above the horizon. 

Here is a video of shockwave on an A320 on youtube (thanks to @mins for finding it).



Thanks for sharing those really nice pictures! I have tried to make some in the past but I couldn't make out the shock effect from all the dirt on the window.