Maya: Clouds in the Sky
You can simulate earth and sky by two large horizonatal planes, close to each other, a blue one for the sky and a brown or green one for the ground. When you place your camera in between the planes, you already get a notion of a natural landscape.
In this tutorial I demonstrate almost super realistic looking clouds, provided by Maya's Fluid Dynamics engine. I render the scene with a Physical Sky using Arnold.
PS: Excuse my lousy placement of the houses on the ground: I used MASH without really thinking about Pivots etc.