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Joined: Sep 2001
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Carpal Tunnel
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Carpal Tunnel
Joined: Sep 2001
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And it's not really belaboring the obvious. It's pointing out interesting evidence. (I don't know anything about the history of clock making, but your point is interesting enough that I'm about to google the subject.  )
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Joined: Mar 2000
Posts: 11,613
Carpal Tunnel
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Carpal Tunnel
Joined: Mar 2000
Posts: 11,613 |
I have been privileged to see the famous bat colony of Austin, Texas, emerge--once. I was too awed by the sheer numbers (up to a million and a half) to actually notice whether they wheeled clockwise or not, but as I cast my mind back, the image seems to be clockwise. Here's a link that explains about drag, lift, and thrust. Possibly these are subject to the Coriolis effect. http://www.ucmp.berkeley.edu/vertebrates/flight/physics.htmlHere is a link to the first of 5 or 6 pictures of them emerging. But if anyone can tell which way, you're a better observer than I am. http://www.pbase.com/image/264541
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Joined: Dec 2000
Posts: 13,803
Carpal Tunnel
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Carpal Tunnel
Joined: Dec 2000
Posts: 13,803 |
Possibly these are subject to the Coriolis effect.
The reason that small scale phenomena don't show a noticeable correlation to Coriolis forces is that the Coriolis forces are small compared to other conditions. In the case of the sink drain, filling the sink from an off center tap will set up motion in the water that will not damp out before the drain is opened. If the water is circulating clockwise it will go down the drain clockwise. In the case of tornadoes, local topography will have a greater effect on the air flow than Coriolis forces will. The same is true for any aerodynamic forces that the bats will experience.
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Joined: Jan 2001
Posts: 13,858
Carpal Tunnel
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Carpal Tunnel
Joined: Jan 2001
Posts: 13,858 |
Here is a very long list of links to bat sites. Well worth browsing. I found one picture of a lot of bats flying at dusk, but they did not appear to be circling. http://www.batbox.org/old_bat_house.html
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Joined: Sep 2001
Posts: 872
old hand
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OP
old hand
Joined: Sep 2001
Posts: 872 |
Jackie, the Austin bat colony of 1,500,000 that you saw is said to rise from their roost in the bridge counterclockwise. And so says this from the National Park Service...
"Hundreds of thousands of Mexican free-tailed bats, whirling counterclockwise, spill forth from a gigantic hole in the earth and are silhouetted against a colorful desert sky ... this is the bat flight experience at Carlsbad Caverns National Park."
And faldage, yes the coriolis effect is small on small sized structures but it tugs with unrelenting persistence. Animals that fly especially need every economy of energy that they can get.
By-the-way, in the morning after the night of feeding, the northern hemisphere bats fly back home, but they don't screw themselves (clockwise) back into the cave, instead they dive in a straight line to the mouth of the cave and on to their roost.
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Joined: Dec 2000
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Carpal Tunnel
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Carpal Tunnel
Joined: Dec 2000
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Animals that fly especially need every economy of energy that they can get.
The point is that other forces swamp the Coriolis forces. It's not that it isn't there or that the samll animals can afford to ignore it; it's the fact that other things are more important at that scale.
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Joined: Jan 2001
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Carpal Tunnel
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Carpal Tunnel
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Dear Milo: I have looked at a lot of the sites. I finally saw a picture of the narrow gaps between
the concrete blocks that make spaces the bats can use in large numbers. I wondered how it
could be possible for the narrow range of temperatures the bats need.
One thing: I wonder how far the bats have to fly for all of them to find enough insects. It must
be quite a distance, covering a very large area.
Dear Milo: I have a new theory for you. One of the sites said the bats are classified as primates.
Is is possible that like humans they are right "handed", and have the right wing slightly more powerful
than the left, which would tend to make them circle to the left, counterclockwise? (taking my tongue
out of my cheek.) i'm sure Faldage will agree with me that is more probable than the Coriolis force.
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Joined: Mar 2001
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Carpal Tunnel
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Carpal Tunnel
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anti-clockwise here, although the main clock in my house runs in the direction traditoinally called anti-clockwise.That's because you guys Upunder dwell in counter-matter! 
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Joined: Mar 2001
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Carpal Tunnel
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Carpal Tunnel
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Well, milum, you could always look at it this way...no matter which direction the bats fly in...guano is still guano!
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Joined: Sep 2001
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Carpal Tunnel
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Carpal Tunnel
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Here's an elementary bat quiz that none of us here would have any problem in scoring 100% on. The quiz is set up so that you can pretty much tell the answer without knowing it, but you might have a child somewhere who'd like to take the quiz. Do not go to this site if you're not curious about elementary bat quizzes! http://www.cccoe.k12.ca.us/bats/quiz.html
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