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| Vine around tree |
Urban legend has it that a bathtub whirlpool spins one way in the Earth's northern hemisphere and the other way south of the equator. Not true: the vortex of an open drain doesn't spin consistently one way or the other. However, natural water currents and air masses are influenced by the
Coriolis effect, which creates so-called
inertial circles that rotate clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere. [NB: For some reason, low pressure weather systems always spin counter-clockwise in the North, clockwise in the South. Go figure...]
The riddle: Here in Waxhaw, NC, most vines, as viewed from above, grow around a tree in a clockwise fashion, like the water and air currents. My question is, does the Coriolis effect influence the path of a vine wrapping around a tree, such that a
hemisphere effect occurs? In other words, do vines spiral
counter-clockwise in the southern hemisphere?
Now, we just need a comment from someone south of the equator.
We're waiting...
≈ ≈ ≈
I can just see you, sitting there tapping your foot until someone answers.
ReplyDeleteI don't do this for everybody.
ReplyDeleteSeems that a researcher has found that vines take a left-hand route (at: http://tinyurl.com/dxq2bts )
And this situation apparently holds above or below the equator.
Some folks say that the Coriolis effect only has an impact on weather objects or water of immense dimensions, such as the Gulf Stream etc. However, it has been observed that hurricanes can take both spin directions in the same hemisphere. At: "Fact or fiction?: South of the Equator toilets flush and tornadoes spin in the opposite direction."
http://tinyurl.com/3f6og3j
Now, I have to admit that I've been twisting my brain, trying to figure out how vines twist around things. Not that I can't see that they do, but I'm trying to figure out how one can tell if the twist is clockwise, or anti-clockwise. If you are at the base of the tree that you have in the picture, and you look up toward the sky (that's what a vine does; take my word for it), the vine is going in a counter-clockwise direction. If, howevr, you look down at the same vine from the top of the tree, then it is twisting in a clockwise direction.
From the side, if the vine slants 45 degrees (assume you are measuring the angle with a protractor, and the tree is centered on the 90-degree line), then the vine is wrapping (remember: from the base) in a clockwise direction. If the vine is taking the "left" angle, then it is at 135 degrees, and is going anti-clockwise.
Say, this stuff is driving me wackko, and is definitely not good for my mental health. Why, just because of you, John, I'll never look at trees in the same way in the future. And for a good reason: I'll be looking at the ground, so that that I can find any Indian arrowheads lying around. Why, had I been looking at vines around trees that Winter of 1978, when Gaby and I were visiting ouy at Stoney Creek, I would have missed that arrowhead I found!
(Is Rachel still ticked off, that I found it?) As I remember, you said she had been looking all Summer for one.
My goodness: '78. John, that's 34 years!
I think I need a beer.
-- John B.
You don't need a beer. You need a life! Again, your comment dwarfs my original posting. Maybe you should "Tweet" your messages, i.e., 140 characters and no more!
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