[justa-hairyape]

Oh. And you see how this example contrail is lighted on its bottom side. Very bright. Why is that ?

[TigersEye]

That contrail is also pretty doggone skinny at the bottom. No comparison.

[RobRoy]

>>Oh. And you see how this example contrail is lighted on its bottom side. Very bright. Why is that ?<<

I found your question.

Simple question. Simple answer: The sun.

The aircraft is high enough in the atmosphere to still be in sunlight. It is why the cloud is lit up as well.

BTW, that looks like a missile. Notice the “corkscrew” pattern?

JK. :)