[justa-hairyape]

The bottom of the plane is reflecting bright light because it is at ~35,000 feet and NOT on the horizon being blocked by haze. It is still in daylight and we get an unobstructed view.It is, and should be, quite bright.

Look closely at the image I posted. The dark bottom of the contrail goes all the way to the bright spot on the object. The dark bottom of the plume is at the object. Caused by shading, not some haze theory.

As I said in posts two days ago. I have seen this phenomenon even when there is NO contrail.

Fine. Post an image of that specific phenomenon occurring on another plane at altitude. This flight comes by every day, right ?

[TigersEye]

The dark bottom of the contrail goes all the way to the bright spot on the object. The dark bottom of the plume is at the object. Caused by shading, not some haze theory.

Yep.

[RobRoy]

>>Look closely at the image I posted. The dark bottom of the contrail goes all the way to the bright spot on the object.<<

OK, I re-examined your photo. I noticed a couple of things. First, it is the TOP that is dark, not the bottom. That is because the sun in the background is below the contrail. Second, in that picture at least, there is a gap between the contrail and the bright spot.

It makes it look even MORE like an aircraft contrail.