Modeling clouds

I am learning to model environments and the problem I face most of the time is that the clouds (Using cloud textures in world settings)look too artificial. Can anybody provide help or links to tutorials that describe creating realistic clouds like in the attached picture(by malefico). http://www.malefico3d.org/imagenes/artwork/still/faro-final.jpg Thank you.

You could perhaps use a 2d image creation program like the gimp or photoshop and then use some cloud brushes from, say, here or here.

there are lots of ways to do this sort of thing.
you could add the clouds with the gimp after rendering, or painting/touching up a photo and adding it to the background in the world settings, or putting a gigantic plane set to shadeless with cloud texture, or making a large particle cloud in the background?

Try a displacement map technique. Use a cloud tex as your displacement, applied to various high-poly ellipsoids or spheres in your scene, subsurfed a couple of times. It works wonders.:RocknRoll:

Those actually look more like an image that was cut and pasted to me. If you look closely. But that is just the feeling I get. It looks like they were drawn or painted and then modified a bit. But then again I am crazy.

you can try creating planes with alpha maps to simulate different layers of clouds…
add a bit of translucency to the material to emphasize the effect…

there is no way currently to create ‘volumetric clouds’ (although there have been some development in this area - look for simphysics branch)