It's a relatively common phenomenon in hydrodynamics (specifically, the formation of large separated cyclones in unstable flow), and the best explanation is del

It's a relatively common phenomenon in hydrodynamics (specifically, the formation of large separated cyclones in unstable flow), and the best explanation is delightful -- Onsager's "The Little Vortices Who Wanted To Play" (a letter to Linus Pauling, reproduced on page 33 of this PDF: http://bactra.org/sloth/eyink-and-sreenivasan-on-onsager-on-turbulence.pdf http://bactra.org/sloth/eyink-and-sreenivasan-on-onsager-on-... ).