Again, inspired by Hannes, and curious if I could make it work (though I don't like working on animations, as you have to wait until the sequence is rendered). For foam to work nicely, there should be some kind of delay after it is formed by the highest peaks, so they die out slower than the ridges subside (and gather in clinging patches which are independantly blown away by wind, pffff). Needs blue math, I guess.