On Dec 23, 2008, at 4:17 PM, [email protected] wrote: >> I'm sure there's chaos involved in that somehow. :) > > Why? It sounds like a pretty clear pattern to me, not chaos.
Unless the fluid flow is completely laminar (which is extremely rare in nature), there's turbulence involved, which is naturally chaotic. Which is why I mentioned that that was a less informative answer than it might appear. (i.e. it was a joke .. :) >> My guess is that if you were able to sample the wind speed at that >> point, you'd see something rather fractal, probably a 1/f >> distribution. The periodicity probably is a long-wavelength >> resonance, though, sort of like seiches in lakes .. > > OK, in what sense are you talking about fractals here. In > particular, why > shouldn't standard wave theory work? > > Dan M. I suppose it might be somewhat applicable, if there was a large air mass that was undergoing some sort of harmonic resonant oscillation triggered by the energy of the frontal air mass. Now that I've had time to think about it, it's probably more likely that the periodicity was due to a shifting vortex street like the one to the leeward side of a small island in this photo: http://earthobservatory.nasa.gov/images/imagerecords/8000/8805/glory_amo_2008141_lrg.jpg .. large vortices like those *can* generate some periodicity in the wind, especially if it's shifting. If it were wave action, also, I'd expect some reverse flow in the cycle at least right after the front arrived. From the description, it sounded more like the wind speed varied between zero and maximum in one direction .. (to OP) right? _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
