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Solar magnetic field reversal

  1. Jan 7, 2016 #1
    Hello everyone

    I have a question: I know what alpha/omega dinamo is, and I think I have understood how this model explains Joy's law and Hale's law, but I don't get how it allows the magnetic field to become poloidal again (after having become toroidal due to differential rotation) and with the opposite polarity with respect to the beginning of the cycle.

    Thanks everyone
     
  2. jcsd
  3. Jan 10, 2016 #2

    Chronos

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    Given we have never observed any obvious consequences of a 'magnetic reversal' in this, or any other solar system, there is room to doubt it is a significant factor.
     
  4. Jan 23, 2016 #3
    I'm working on this. I'll report back if I can figure it out.
     
  5. Jan 23, 2016 #4

    The toroidal field can be twisted by the helical turbulence (associated with convection in a rotating frame) to give back a field in the poloidal plane.

    -- Astrophysics for Physicists, by A.R. Choudhuri.​

    In my opinion the "poloidal" and "toroidal" terms are unfortunate. IMO the two fields would be better associated with the major and minor axes of a torus. But this nomenclature ain't gonna change.

    Why doesn't it find an equilibrium? It's because magnetism is essentially a sideways force. Like Prince's mother, she's never satisfied. Magnetism in a plasma always wants to be sideways of whatever it is doing at the time.
     
    Last edited: Jan 23, 2016
  6. Jan 23, 2016 #5

    davenn

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    Chronos
    he/she's referring to the reversals of the 11 and 22 year solar magnetic reversals that of course have been well studied
     
  7. Jan 24, 2016 #6

    Chronos

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    The point remains, are there any observed affects of significance? I think not.
     
  8. Jan 24, 2016 #7

    Dotini

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    Are not sunspots related to the solar magnetic cycle?
     
  9. Jan 24, 2016 #8

    davenn

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    yes lots of observed effects

    do you not follow the solar cycle and its effects on earth ??

    but that is still irrelevant as far as the original Q is concerned
    you are taking the thread off topic
     
  10. Jan 30, 2016 #9
    @Hornbein

    Ok, but how does this turbulence restore the polodial field? This is written everywhere but no one explains HOW this happens
     
  11. Jan 30, 2016 #10
    I don't really know. Might I suggest you read that book? I haven't gotten around to it yet.

    But if you want the cheap stuff from somebody with a weak grasp on the subject, the way it works is that magnetohydrodynamics is fundamentally unstable. The moving plasma induces a force on itself at right angles to the way it is moving. So it ain't never satisfied. If its toroidal it wants to be poloidal, and vice versa. At least, so I gather.
     
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