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Atmosphere's Rotation

  1. Aug 26, 2011 #1
    I was thinking about the rotation of Earth when I came across to know that the atmosphere moves as the Earth rotates. They move as the same body. But then a question came into my mind. Is the speed of the rotation of the atmosphere same as that of the Earth. And when we jump, why do we fall on the same location from which we jump, that is jump vertically ?
     
  2. jcsd
  3. Aug 26, 2011 #2
    Let me try this explanation.

    The Earth and the atmosphere do not rotate at the same speed. At ground level calm, static air might move close to the same speed as the Earth, but because of the differences in density the Earth moves through the atmosphere not with it. Without this fact there would be no wind.

    Part two.

    When we jump vertically we do not land in exactly the same place each time. We land either slighty ahead, behind, or too one side of our initial launch point. Due to the fact that we gain very little alttitude in a vertical leap, (and do not leap exactly vertical) there is just very little noticable difference in our landing spot.
     
  4. Aug 26, 2011 #3
    On the other hand some related effects are larger than might be expected with just superficialthought:
    http://en.wikipedia.org/wiki/Coriolis_effect#Draining_in_bathtubs_and_toilets

    You can also experience rotational effects when traveling from East to West versus West to East via airplane: travel time in the former direction takes longer than the latter.
     
  5. Aug 26, 2011 #4
    Just to clarify, the Coriolis effect is not responsible for the direction a toilet flushes. That's a myth spread by people who care more about being interesting than being accurate.
     
  6. Aug 26, 2011 #5

    Drakkith

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    Overall, the atmosphere moves with the Earth's rotation. Because air is a fluid it can have currents and layers and all the different properties that it has.

    As for jumping, we fall to the same spot because we are also moving with the Earth's rotation. Because of the size of the Earth the curvature on our scale is very very small, so the Earth doesn't "fall" away underneath us while we are in the air.
     
  7. Aug 26, 2011 #6

    Drakkith

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    I don't really see how this is correct. Are you sure it doesn't have something to do with the jet streams?
     
  8. Aug 26, 2011 #7

    cjl

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    It's true that travel times vary substantially depending on direction, but it is 100% to do with the jet streams.
     
  9. Aug 26, 2011 #8

    Drakkith

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    Yeah, that's what I thought. The wiki article on jet streams shows them all travelling in a west to east direction.
     
  10. Aug 26, 2011 #9

    A.T.

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    Or by people with very large toilets.
     
  11. Aug 26, 2011 #10

    boneh3ad

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    The wind is NOT a result of the Earth "traveling through the atmosphere."
     
  12. Aug 27, 2011 #11

    HallsofIvy

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    Short answer- conservation of momentum. While we are standing on the earth we have the same momentum as the earth itself- we are moving east as fast as it is. When we jump, we still have that momentum and are still moving to the east as fast as the earth is.
     
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