I have a script right now using the Cloud Generator add on. Whenever I have clouds that overlap the render comes out as the following:
They look fine however when they do not overlap:
Attachments
In edit mode, duplicate several times and shape Cube into something resembling your cloud scene. Cube mesh copies can overlap or can be separated by some space.
Press the button.
You can’t have overlapping domains. All your clouds should be one mesh contained into one Domain.