VDB Sky
VDB Sky Daz 3D model
VDB Sky allows you to paint your atmosphere with fully-customizable cloud patterns. There is a grid network of clouds that snap together, solo clouds, storm clouds, lightning strikes, and lighting presets. Each prop can blend seamlessly into outdoor HDRIs or even the Iray sun/sky mode.
There is also a suite of tools to modify the density and brightness of your clouds to further blend them into your scene.
https://www.daz3d.com/vdb-sky