I downloaded some new tools and was trying them out. This is the result of a pair of 'cloud' brushes. I can see some alternative uses of them in regards to texture, but I like how they look for their intended use, too.
I don't use the 'add (glow)' blending layers very often because it tends to be obnoxiously saturated most of the time, but for this case it helped give the clouds some interest and depth.