Would you care to explain how a ground based GPS signal's relative velocity changes so as to cause a blue shift as the "satellite" appears to move towards the observer, change to neutral as it appears overhead and then shifts towards red as it appears to move away?
I already have. Again, it's up to you to actually follow up the links I sent you and catch up on the elementary principles behind the Doppler effect and the atmolayer's existence. Trying to explain things to a guy who thinks air doesn't exist is not something I'm interested in.
No, that's not how you do. If you interpret scientific fact, and your understanding of it is questioned, you cannot simply say "I provided the same facts, read them yourself", simply because the facts that you refer to are used to support a theory that is, with all fairness, wildly frowned upon and from a scientific standpoint, very far fetched.
This is why, you as a provider of facts, HAVE to explain how these are to be interpretted, and add a reference as to how they support the theory you're standing up for. Science is about supplying evidence that are to CONVINCE your fellow scientists about the correctness of your facts, which through appropiate methodology and observation can be reproduced. This is a mantra, and the only rational mantra.
Flat earthers have a tendency to just leave links to articles they dont give the impression to really understand themselfs, and imply bigotry to those they address. That's why you, on the convincing side of the table, HAVE to explain.
With what you've said so far, all you do is leave the impression that you, in fact, don't really know, which is why it is so easy to disregard what Flat earthers say in general; Because of the lack of any evidence what so ever.