There is, of course, but it's BELOW the local horizon. It's lighting the clouds from the bottom. In fact, the first headline anyone wrote on this event was "Missile Lights Up LA", and that's what they were referring to.
When you look at the area ABOVE the clouds, it's darker because it's SHADOWED by those clouds.
There are also clouds in the foreground that are totally within the Earth's shadow of course, but they have nothing to do with much of anything except they are at a far lower altitude and are not between the object and the Sun.
So, yes, that proves the object is traveling from West to East ~ and we know that because the cirrus clouds in the distance are between the contrail and the Sun over the horizon.
For what it's worth, I live with a person who literally makes a living understanding lighting and perspective with regard to aviation. He could certainly be considered an expert. He has watched this video many times, and shakes his head everytime at folks who don't see what to him is obvious from the lighting. But then again, because he taught lighting and perspective at college levels, he does get that for some people (yours truly, for example!!!), the art of visualizing objects in motion in 3-D comes very slowly and with much patient explaining. HE is not arrogant, you see. For that matter, I don't think you are either, Mu, and I appreciate the lack of it in the tone of your posts. You stand apart in a good way from a lot of the contrail-hyping folks I see here, who show a level of arrogance that is stunning.
The entire contrail has the consistent dark and light pattern. Due to sunlight and self shading. The image from another event from December 31st has a cloud shading parts of its plume. But that is understandable, since it appears to be a plane. Perhaps you are confusing the two.
So, yes, that proves the object is traveling from West to East ~ and we know that because the cirrus clouds in the distance are between the contrail and the Sun over the horizon.
We have low lying clouds all the time here off the coast. Sometimes they even come down to sea level. Called marine layer and fog. Have even seen low lying clouds moving one direction, and higher clouds above them moving in the opposite direction. Welcome to the mountainous coastline of the largest ocean in the world.