usually when it comes to clouds there are 2 major obstacles, edges from soft to hard and the volumetric lighting it has in the shape. So in order to create a nice alpha edge i extracted and created brushes from flat top down sattelite images of major hurrican storms. After that you just painted in the major cloud shapes and added in additional cloud detail from airplane shot images. The landmass alpha required hardedged brush.
the most difficult part was actually the comp rather then the painting, with the earth rotation. I think the edit is to short to notice much of the correct movement.But since the commercial is around 90s there were tons of shots that needed to fit in.. Plus the final grade they put on is more purple ish