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Why do leaves fall off trees in fall?

Just for kicks: Can you give me an astronomical reason for why certain trees drop their leaves in the fall?

  • Answer:

    I think this is what you're after. It is an accident of astronomy that our earth has a tilt of 21.3 degrees. (That's the current tilt ... it ranges between 21 and 25 degrees every 41,000 years.) As a result, trees far away from the equator see a variable amount of sunlight over the course of one journey around the sun (one year). Trees (such as palm trees) near the equator (specifically between the tropics) do not see much variability in the sunlight, so the following does apply to them. When tilted towards the sun, the days are longer, and the sun higher in the sky, and the tree wants as much area dedicated to photosynthesis as possible. So leaves are good. But when tilted away from the sun, the days are shorter, the sun not as high up, and photosynthesis is more difficult. The leaves are a premium ... they're consuming more food than they are producing with photosynthesis. Plus, with temperatures dropping, water in the leaves is in danger of freezing, which burdens the branches with so much extra weight that they can break. So it is better to shed those leaves for that part of the journey around the sun. (This is less of a problem with trees, like pine trees, that have needles instead of leaves.) Is that what your after? (Great question!)

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One reason is that not all leaves contain the same amount of Chlorophyl,that substance that prevents freezing.Those with less will drop their leaves. At the same time they are providing nutrition on the ground for the future.I would say that the tree are very smart.So their evolution was inteligently done.That is why the tree are so smart. Tree life contains an interesting control system in the Dna code wich causes the phenomena to happen.

goring

They drop their leaves in relation to the length of the day with the days growing shorter in the fall. I used to live in Hawaii and the leaves fall from those trees even though the temperature stays much the same....so I looked it up once out of curiousity.

Surfgirl2go

Days shorter - less sun

purple dove

insufficient sunlight

mrsdebra1966

winter - less light

Foo

Its all about time and cycle. The entire universe runs on this. Everything must have a cycle in order to preserve balance. A tree is no exception. It has a cycle. We name parts of the cycle: Winter, Spring, Summer and Fall. We recognize them by what happens during those phases. Through out the universe there are signs of this that we can see. Look through your telescope and the arrangements of the stars and constellations. These patterns move like a giant clock and will never stop. Even if our universe ends, it is but a speck on a larger and larger canvass. Enjoy the big picture.>>>

thewildeman2

All trees do except pine trees, xmas trees. All trees with leaves lose them in the winter and come back in the summer.

blondie

During the earths 360-day rotation around the sun there is less hours of sunlight in times on the year. Then the days become shorter and the nights become longer. The temperature slowly begins to fall then comes winter

edd_805

The angle of the sun triggers this phenomenon once the earth starts tilting for winter.

Herman707

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