Clouds?

DEElekgolo

I am currently working on a sky for a considerably old game engine and I am wondering how I would approach making some nice 3d looking clouds for it? The game engine is from halo 1and does not support particles for the sky. Currently the sky is just a scaled down sphere with a bunch of textures scrolling across it with the add property. The clouds do move in 1 direction. And the horizon is not see-able by the player.
Here is what I have now.

Eric Chadwick

You could probably get away with a 2-layer setup. That's how this was done.

The behind/top layer is lerp (could also be subtract or multiply) so the upper clouds are dark. The front/bottom layer is additive so they're light-colored. They're also offset slightly, so the additive layer makes it look like they're lit from the side. The gray streaks are a third layer.

I would also suggest using a fractal perlin noise, which looks puffier than what you have.