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Wind farms can cause climate change

Discussion in 'Environmental Discussion' started by zenMachine, Apr 30, 2012.

  1. austingreen

    austingreen Senior Member

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    According to some we are doing that experiment:D

    But here is the big question, is it better or worse if wind farms do not cool off as much at night or if the earth spins faster or slower.

    I don't really know the answer to that question, but things will be definitely worse if the antartic icecap melts. Will we only be able to see penguins in the zoo?
     
  2. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    And no cheating (i.e. farting).
     
  3. icarus

    icarus Senior Member

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    Don't mean to rain on the parade, but we are already melting both the arctic and Antarctic ice caps! IMHO, seeing penguins at the zoo might likely be the least of our worries,,penguins might see the issue differently.


    Icarus
     
  4. austingreen

    austingreen Senior Member

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    Hey just because they are not in the bible is no reason to hate on penguins:D
     
  5. icarus

    icarus Senior Member

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    No hate on penguins here,, only stating the saddly obvious,, that penguins are going to pay a higher (and quicker) price for our carbon foot print than we will. (and the penguins can do little or nothing about it,, just as they have done little or nothing to cause it,, a John Prine said, "it's a big old goofy world!"

    Icarus.
     
  6. austingreen

    austingreen Senior Member

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    You probably didn't read the top of my post which says they may already be melting, or understand the joke nature. The question of if damns cause changes of rotation speed of the earth is entirely academic, and if you get the wrong answer nothing bad happens. Its a crazy thing to just worry about what is natural or what should be. I'm not sure what the original source is

    The State - Episode 301

     
  7. fuzzy1

    fuzzy1 Senior Member

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    Engineer. Pretending to be retired much of the time now, working when I feel like it.
    This would have been an appropriate quiz question in several courses I took. But it wasn't, and that was decades ago, so I don't know that my answer is correct.

    For this question, an elevated ice mass is equivalent to a water reservoir. Assuming this mass is depriving the ocean surface of a thin shell of surface water (and assuming a spherical earth with no land mass interference to complicate the math), any reservoir between roughly latitudes 35N and 35S is equivalent to pushing some mass farther away from the spin axis, slowing the spin rate. Reservoirs closer to the poles than latitude 35, including the ice sheets on the Antarctic plateaus, effectively pull mass closer to axis, speeding it up.

    Thus, I'm claiming there is a neutral band around latitude 35. A single reservoir will cause some wobble, so a wobble-free solution would need several installations distributed appropriately around the globe. Actual neutral latitude also depends on elevation, but that detail is lost in the rounding.

    The bulk of civilization's water reservoirs are north of 35N, hence the net speed-up.
     
  8. austingreen

    austingreen Senior Member

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    Deep breath, we are slowing down, but building the damns makes us slow slower:D Breath out

    Dams for Water Supply Are Altering Earth's Orbit, Expert Says - NYTimes.com
    Melting greenland and antartic ice sheets should shift water towards the equator, slowing rotation, but again very little. I have no idea what you are talking about with latitude 35. If you hold water furthur from the equator less will be at the equator.
     
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  9. drees

    drees Senior Member

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    Think about what happens if you take a lot of water from the ocean and pile it up on the Earth's north or south pole... So I was wrong in my quick guess that it was a trick question - you just need to figure out what the correct latitude for all your elevated water is to perfectly balance the water you took out of the ocean. What's funny is that I was half-way there with my ice melting question - melting land ice on Antarctica will just slow down the Earth's rotation further, not speed it up!
     
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  10. SageBrush

    SageBrush Senior Member

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    Fun physics:D

    I imagine the problem in terms of latitudes. Before we displace water with a dam, a shell of water surrounds the center of gravity, than can be broken down into a series of (infinite) rings. Which ring (latitude) is it such that the sum of the distances from the center to the ring before it and after it are equal ?

    I solve the question by integrals, but I am haunted by the likely possibility that a simple geometric solution exists :rolleyes:
     
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  11. El Dobro

    El Dobro A Member

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    So, is it true that penguin meat is tasty?
     
  12. HaveNoCents

    HaveNoCents Conservative Tree Hugger

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    Only when grilled on charcoal.

    Also it's a proven fact that the turbines are acting as the earth's propellers. This is why we haven't done much space exploration. We are going to use the whole planet to visit other galaxies. :)
     
  13. El Dobro

    El Dobro A Member

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    So, frying isn't recommended? I was thinking KFP.
     
  14. SageBrush

    SageBrush Senior Member

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    Yeah, now I see the simple geometry solution. I had to stare at a door for a while :) :)

    The sum of the torques can be represented by an equilateral right triangle, so the question (of why 35 degrees) is just asking us to break the triangle into two equal areas, with the break perpendicular to one of the not hypotenuse sides.
     
  15. fuzzy1

    fuzzy1 Senior Member

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    The NYT reporter and headline writer botched the wording. This changes only earth's rotation on its axis, not is orbit around the sun.
    The NYT article is correct in that what matters is the distance from the spin axis. For angular momentum purposes, the weighted average of the earth's surface is about 3230 miles from the axis, corresponding to the surface just past latitude 35 degrees.

    The surface equator is about 3960 miles from this axis, so moving 'average' water there slows down the spin. The poles are obviously at 0 miles, so moving water there speeds up the spin. Reservoirs in my region are about 2700 miles from the axis, closer than ocean 'average'.
     
  16. austingreen

    austingreen Senior Member

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    Oh, you want a single number. It depends on how high above sea level the reservoir is and the latitude. IIRC 3 Gorges is about 150 meters above sea level and it slows the rotation slightly, as well as moves the axis slightly and adds a little wobble. The answer depends on the real shape of the earth and the distance from the axis. From 3 gorges I can guess its above 30 latitude at sea level, but would need more information about the moment of the earth as sea level changed to get a more exact answer. I'm sure you can email someone at nasa or noaa and they can tell you exactly.

    Fuzzy,
    I see now you have answered. I didn't even noticed the NYT reporter was wrong on the title, it just was the first google link, as I honestly didn't know were the dams all were located. If you have factored in the obloid shape that should be correct. I don't think I actually know the precise shape to do a calculation.
     
  17. austingreen

    austingreen Senior Member

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    An African or an Antartic penguin?
     
  18. fuzzy1

    fuzzy1 Senior Member

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    Neglecting the oblate spheroid issue, these two number can easily be combined into a single number: distance from axis = cosine(latitude) * (radius(earth)+ elevation). In most cases, elevation is such a minor factor that it can be ignored.
    I did not correct for the shape, nor for the non-uniform land distribution that interrupts the thin shell of ocean surface. Those would be advanced topics.
     
  19. El Dobro

    El Dobro A Member

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    Antarctic, they're plumper.
     
  20. austingreen

    austingreen Senior Member

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    .
    cool so 35.3 degrees for you if water is a thin sphere (2/3MR2 moment), call Noaa for to know the real moment of the water:D. The number is so small I would want to correct. If I'm going to that level of detail I would want to know how gravity effects the moment.

    I was confused by the 35 because it was so round