A Terragen 4 render using new cloud shader, 

I used Heightfield Merge shaders with several different terrains for this, some interesting results can be found by adjusting the displacement merge modes and varying the blending of the terrains to be mixed.  All images I post processed  with NIK suite by Google, I couldn’t really decide which one was my favourite, though I think it is probably the last one?

feel free to download the images on the links below…

1. full view
2. full view
3. full view
4. full view

Thanks for looking!