Where is this located? Cannot find it. I tried to make a post on COH2.org forum, but it wont let me create a new topic for some reason. I did ask in a reply, but I havent gotten an answer yet. Thanks!
EDIT: After getting a post on COH2.org, I think Ive made progress, from some helpfull answers.
In the heightmap editor, there is a check box, for "top layer". Use just like altering terrain. Make sure, in atmosphere properties, that the depht, texture, and details are defined, or it will not work as intended.