How Does Turbulence Restore the Poloidal Magnetic Field in Solar Reversals?

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Discussion Overview

The discussion centers on the mechanisms by which turbulence in the solar environment restores the poloidal magnetic field during solar magnetic reversals, particularly in the context of the alpha/omega dynamo model. Participants explore theoretical aspects, implications for solar phenomena, and the understanding of magnetic field configurations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants express confusion about how the alpha/omega dynamo model facilitates the transition of the magnetic field from toroidal to poloidal, particularly after differential rotation.
  • One participant references a source suggesting that helical turbulence can twist the toroidal field back into the poloidal plane.
  • Concerns are raised about the lack of observed consequences of magnetic reversals in the solar system, leading to skepticism about their significance.
  • Another participant questions the relevance of observed solar phenomena, such as sunspots, to the original question about turbulence and magnetic field restoration.
  • There is a suggestion that magnetohydrodynamics is inherently unstable, leading to a continuous transition between toroidal and poloidal states.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the significance of magnetic reversals or the clarity of the mechanisms involved in restoring the poloidal field. Multiple competing views and uncertainties remain present throughout the discussion.

Contextual Notes

Some statements reflect a lack of clarity regarding the definitions and implications of poloidal and toroidal fields, as well as the specific effects of turbulence on these configurations. The discussion also highlights varying levels of understanding among participants regarding the underlying physics.

astrolollo
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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
 
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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.
 
astrolollo said:
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

I'm working on this. I'll report back if I can figure it out.
 
astrolollo said:
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
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 going to 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:
Chronos said:
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.

Chronos
he/she's referring to the reversals of the 11 and 22 year solar magnetic reversals that of course have been well studied
 
The point remains, are there any observed affects of significance? I think not.
 
Chronos said:
The point remains, are there any observed affects of significance? I think not.
Are not sunspots related to the solar magnetic cycle?
 
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Chronos said:
The point remains, are there any observed affects of significance? I think not.

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
 
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@Hornbein

Ok, but how does this turbulence restore the polodial field? This is written everywhere but no one explains HOW this happens
 
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astrolollo said:
@Hornbein

Ok, but how does this turbulence restore the polodial field? This is written everywhere but no one explains HOW this happens

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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