That's an unusual way of doing it, that idea never came to me. What is the supposed benefit to that, since you cannot have it moving, or it would become obviously ugly?
Have you tried cloud layer that is affected by daylight? Otherwise I would just make another for night, like Torque3D does now with the night skybox.
You could also use a very large cloud layer with lots of variants so you occasionally get cloudy areas and clear areas, which then move all over the map, which is also more realistic, since the very cloudy areas can also be over your head. To the simulate the more cloudiness at the horizon you can use fog.
In BeamNG i use TOD all the time so the clouds *need* to be effected by daylight, even though i rarely use night in the game. Ideally for me they would be able to rotate but personally i dont mind if its static. Its a cheaty way to create the feeling of built up clouds at the horizon without having to use cloud layer normals maps, it hard to get those looking as good as actual photos of horizon clouds. Ive added a cloud layer to have moving coulds too but the horizon clouds are meant to just stay at the horizon, no matter what TOD it is.
I cant use a diffusemap/texture for cloud layer right? I thought it always had to be a normal map? Im not at my home computer now but i quickly tried and had no success using the .png ive used for the basic clouds in the screenshots. Also, i didnt think i could align cloud layer textures to be centered on the sky, so that it doesnt show/loop/repeat the edge of the texture.
The large cloud layer texture is a great idea, thanks, will be a good way to add diversity without using a ton of layers!
To use fog at the horizon i think wont create what i try to create, too much of a sharp edge IMO.