Plasma is just a 2-dimensional Brownian motion. But, what the hell is a Brownian motion? Well, forget it, I'll tell it in other words:
These plasma clouds are generated by a recursive algorithm that randomly picks colors of the corner of a rectangle, and then continues recursively quartering previous rectangles. Random colors are averaged with those of the outer rectangles so that small neighborhoods do not show much change, for a smoothed-out, cloud-like effect.
Plasma clouds are great for color cycling, and great for 3D transformations.