MIMF

I'm constantly amazed at the wonders of nature. Every time I go into the woods I learn something new. Most of these whacky,weird and wonderful characteristics have a very simple basis in commonsense. Why just last week during an exceptionally warm and sunny day here in the Ohio River valley I was lying on my back watching the remaining leaves being loosened and blown from the trees. I noticed a pattern in the directions the leaves were turning as they spiraled and fell to the ground. So I began to count 100 leaves and at least 85% of them were turning counter clockwise. Sure some flopped and some fell like a rock but after counting well over 300 they were mostly spiraling in a counter clockwise just like NASCAR drivers. Like water down a drain most of them went to the left. How many times this must be repeated in trees. How about twisting growth in the bark? How about the twisting growth in the grain of the wood? You might think I'm crazy and you would be right but they turn left. Why ? And what might this have to do with choosing the right wood for a guitar ?

I believe that what you were observing was the Coreolis Effect.
That's what makes draining water spiral down the way it does.
Likely the leaf will flip until it "goes with the flow", and spins the way the earth wants it to.

I’m not so sure the Coreolis effect is very important to something as small as a leaf in a wooded area. There are certainly many more local influences that will have a larger effect. Coreolis has a big influence on large things like weather patterns. Water doesn’t ALWAYS spin the same way in sink drains either. In fact, sometimes you will see two vortices spinning in opposite directions. In a forest, I would expect a nearby hill or valley to funnel wind in such a way to have 1000 times the influence on leaf spinning (in a given location). Of course, I have been wrong before. <G>

Wind should have little affect on the direction of spin of something as small as a leaf. I'm with Chuck on this.

I don't understand your reasoning Barry. I have seen countless exampls of wind swirling one direction or the other (even verry gentle breezes) due to the geometry of the environment. Surely you are not crediting the rotation of the earth for the little leaf tornados you see in the corners of buildings.?. I would think it the opposite, something as small as a leaf would be barely effected by the Coreolis effect which has its forces related to mass. There is a peice of paper on the corner of my desk, I expect that when Margie walked by, she (and the air she disturbed) had more effect than the position of the moon.

Depending on what Margie looks like, she might disturb more than the air.

I'd love to get into a technical discussion of free, falling bodies under the influence of aerodynamic forces in a moving media, but I'm a bit busy with a heap of other technical issues at work right now. Y'all knock yourselves out.

I don't doubt that the Coreolis effect operates on falling leaves, but I doubt that it affects the spin direction.
It affects the direction that water circles a drain, but it does that by deflecting water flowing toward the drain, not by causing it to spin.
Since the leaf is a solid body, the Coreolis effect would push the entire leaf and not affect spin direction.

Chuck, you started this fiasco. And now you abandon me to the hoards?

I'll bite
I've spent a lot of my time sitting in the woods, with not much else to look at but leaves. The "helicopters" from maples all ways spin to the left(or right depending on how high you are in the tree). The oaks tend to just fall and twitch. Locust tends to just flutter. Gum balls tend to just fall with no disernable twist. Walnuts tend to fall on my truck.

Ok, looking into this a bit more. There may be a tiny moment induced on free bodies due to Coriolis effect, but it would really be super tiny on such a small object as a leaf.
Yea ... that's not it.

How you like me now Barry?

I would bet that it has something to do with the leaves themselves, and how they grow. The leaves probably have a certain type of shape, or curl, that makes them turn a certain way when they fall and react with the air.
Tree cell structure is kind of like a fractal, all of the cells "do" a certain thing as they grow...and each leaf will have the same characteristics. How's that for a guess?

See Barry, the hoards aint so bad <G>

Wow, it sure is dirty under this bus!

I thought the hoards would have picked your bones clean by the time you saw the underside of the bus!
my bad

I agree with Mark on this. That was my initial impression when I looked at this thread, but didn't have an opportunity to post my thoughts; I think Mark nailed it.

Mark Swanson wrote:I would bet that it has something to do with the leaves themselves, and how they grow.

I think it has to do with how they're consumed.

Leaves !?
please
We need to be talking about flowers now.

Well this has taken a dark turn. At least I think it has, I'm not 100% sure I know what we are talking about now. You'd think I would be used to that as I usually don't know what I am talking about. . .

Mark is the closest. It is the result of thousands of years of evolution at work. You might want to read "The Botany of Desire". I just us common sense and it says that leaves need to fall within the shadow of the limbs in order that the nutrients when breakdown occurs feeds the root system. The Corealis effect will also contribute over time because the trees that get the most of their nutrients back stay stronger and if the trees with the correct shaped leaves to make this happen will naturally rise to the top of the gene pool.
All things considered go with the big picture. That's the wonderful part.