I read this maybe 30 years ago. IIRC it was a paperback showing some clouds on the cover.
The story: A bunch of Earth people (I want to say scientists) start acting a bit strange and getting odd dreams about an alien world. Then the aliens begin borrowing bodies to get a message through.
Away across the galaxy the delta wing aliens (who live permanently aloft in their world's atmosphere) are panicking as their sun is getting hotter. Their best telepaths are trying to achieve full contact with Earth for help.
A breakthrough happens and they find they can bodyswap with humans, however they find surface dwelling repulsive. The hapless humans find themselves in very hot air in scared flocks of Alien life.
An Earth scientist manages to convince his fellow flyers, of both species, to aid him in a survival plan using some kind of shielding.
That's all I can recall about this book. Help please