Re: Incoming!
On Dec 23, 2008, at 12:34 AM, Doug Pensinger wrote: Speaking of wind, I ran across an odd phenomenon while backpacking in the Sierra Nevada something close to twenty years ago. The wind actually came in waves; it would start out at a low velocity and continue to build over a period of something like 30 seconds at which point it was howling. Then it would stop dead and stay calm for several seconds before repeating. This continued all night then at some point the wind became continuous and later it snowed and we went scurrying for the trailhead. Has anyone else run into something like that, or heard of it happening? It was in early September in the Desolation wilderness south of Tahoe. Doug I'm sure there's chaos involved in that somehow. :) (Not as informative answer as it might sound, LOL) 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 .. ___ http://www.mccmedia.com/mailman/listinfo/brin-l
RE: Incoming!
On Mon, 22 Dec 2008, Gary Nunn wrote: Julia wrote... seriously, there are rabbits in the area, and I'm vaguely phobic about rabbits Have you ever seen the B movie Night of the Lepus? Quite possibly the worst movie of all-time. No, and I think I'll skip that one. Julia ___ http://www.mccmedia.com/mailman/listinfo/brin-l
Why?
Why does moister air carry odors better? (This question occurred to me as I was driving through the fairly thin but thicker-in-spots fog we have at the moment and in a thicker part of it, got the unmistakable odor of Cowfield. And when you've had gym class downwind of a dairy farm, you can't mistake the odor of Cowfield for at least the next 25 years) Julia ___ http://www.mccmedia.com/mailman/listinfo/brin-l
Re: Why?
As I understand it, it's not that it carries odors better, it's that your nose is more sensitive to odors carried in moist air. (Mentioning this because I do at one point remember a gas chromatograph attachment with a nose shield connected directly to the column outlet, with a fan to circulate air slowly through it and a humidifier. Apparently the human nose is *the* most sensitive detector for certain chemicals like mercaptans, which can be detected in concentrations of single digit parts per billion .. but the sensitivity is very dependent on humidity.) No, Cowfield is not an odor one easily forgets. Although I've at times been able to smell the difference between healthy and not so healthy soil in freshly plowed fields, and *known* the healthy soil was healthy. That, and about a dozen or so industrial chemicals, were in my odor library for quite a while after the lab instrument job. :D On Dec 23, 2008, at 12:47 PM, Julia Thompson wrote: Why does moister air carry odors better? (This question occurred to me as I was driving through the fairly thin but thicker-in-spots fog we have at the moment and in a thicker part of it, got the unmistakable odor of Cowfield. And when you've had gym class downwind of a dairy farm, you can't mistake the odor of Cowfield for at least the next 25 years) Julia ___ http://www.mccmedia.com/mailman/listinfo/brin-l
Re: Incoming!
Yesterday was the Summer solstice here in the South Pacific and the day before was cold - only 6 degrees celsius. Global warming harumph. The fact that it is colder in some places than normal may be a sign of global warming. I know that some predictions say that global warming will make it colder and wetter here in our part of California because more cold air will be sucked off the Pacific by rising air in a hotter Central Valley. Global warming will lead to less stable weather and more extremes. Or already is. From what I understand of the models, that's not quite the consensus. Global warming is a long-term trend, not a year by year trend. In addition, we know that the weather had other variables, like the hurricane cycle (30s-40s many hurricanes, 70s-80s few, '00s many, or the La Nina/El Nino variation. Overall, this last year has been the coolest in the decade. This doesn't mean there is more variation than usual. For example, we've not had another dust bowl of the '30s. To first order, one should expect a general warming, and pattern changes with global warming. Most models predict more rain overall. The patterns of drought may not be more vicious, we're just more globally connected now. The data on hurricanes, in particular, is hard to pinpoint, because we can not name a tropical storm that just reaches 40 mph in the mid-Atlantic, or catch a hurricane at its peak of 155 to make it a cat 5, even though it ramped up and down fast, and hit land as only a cat 2. So, if one applies a fairly heavy, say 15 year filter, to the data, one sees global warming. If one looks for general regional trends, they are probably still mostly in the noise, but may energe later (in fact I'd be surprised if none emerged later). Dan M. mail2web - Check your email from the web at http://link.mail2web.com/mail2web ___ http://www.mccmedia.com/mailman/listinfo/brin-l
Re: Incoming!
I'm sure there's chaos involved in that somehow. :) Why? It sounds like a pretty clear pattern to me, not chaos. 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. mail2web.com – Enhanced email for the mobile individual based on Microsoft® Exchange - http://link.mail2web.com/Personal/EnhancedEmail ___ http://www.mccmedia.com/mailman/listinfo/brin-l
Re: Incoming!
On Dec 23, 2008, at 4:17 PM, dsummersmi...@comcast.net 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
