Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Lightning connected with the magnetism of Earth core?

  1. Aug 5, 2008 #1
    Thunder in relation to earths core.

    Is there a relation to how the earths core revolves and circulates regarding thunder? What if one would track the amount of energy beeing surged and what direction it might seem to be heading, if has a direction? Is there a inderect link between lightning and earths magnetism beeing surged from the earths core?

    Any thoughts?
     
  2. jcsd
  3. Aug 5, 2008 #2

    Evo

    User Avatar

    Staff: Mentor

  4. Aug 6, 2008 #3
    "
    "
    Simple enough, however it does not explain why the larger materia forms the negative charge below the lighter forming the positive. It suggests that lightning has a direction, something like the earths core is guiding it.

    Why wouldnt lightning be discharged out in to outer space rather than towards the ground? it woud actualy make more sense if lightning sought itself towards outer space rather than back unto the ground. Ofcoarse this is all speculation, but it would seem the earth cores revolvement in speed and direction guides lightning in both direction and intensity. If one would calculate some kindoff pattern between these two, then it would be possible to calculate what speed and direction the eartch core is currently revolving.

    it seems earths core generates the magnetism causing the discharge motion to be downwards rather than upwards, this would also suggest there is a intimate coaperation between the two.
     
  5. Aug 6, 2008 #4

    russ_watters

    User Avatar

    Staff: Mentor

    Did you miss this part of the explanation?:
    Charges get separated, then discharge to come back to equilibrium. Nothing about the earth's core or discharge to space in there.
     
  6. Aug 6, 2008 #5

    Evo

    User Avatar

    Staff: Mentor

    It does, they are referred to as red sprites and blue jets.

    http://apod.nasa.gov/apod/ap951111.html
     
  7. Aug 6, 2008 #6
    I know this is not directly related, but while I'm here I may as well clear up another apparent misunderstanding for the OP.

    The earth's core is not magnetized. The Earth's magnetic field is generated by the swirling around of liquid in the outer core (driven by thermal and, more importantly, compositional convection) in what is known as the geodynamo.

    In 1819 Hans Christian Oersted observed that a wire carrying a current could deflect a compass needle, this implied that a current in a wire produces a magnetic field. It was later realized that the magnetism in a material could be explained by considering moving electrical charges on an atomic level.

    Ferromagnetism: This is a special case whereby the atomic neighbourhood allows for spontaneous magnetization. In this case, the atomic moments are aligned parallel; few materials are ferromagnetic at temperatures above 0°C, some of which include: iron, nickel, cobalt, gadolinium, and chromium dioxide. In a material such as a rock, small groups of perfectly aligned atoms may exist in a spatial configuration; one of these zones is called a magnetic domain, and has a typical diameter of a few μm, these contribute to the magnetism of a material at a macroscopic scale.


    In a ferromagnetic substance the alignment of atoms depends on a balance between thermal and chemical bonding energy. The chemical bonding energy acts to align the magnetic moments of the atoms, whereas the thermal energy causes the atoms to vibrate out of line. At temperatures below the Curie temperature the bonding energy prevails and the atoms are locked into a formation which enables spontaneous magnetization. At temperatures above the Curie temperature thermal agitation destroys existing magnetic domains such that the material loses its magnetization.

    As pressure is increased the Curie temperature lowers; thus at the core where temperature and pressure are very high relative to the conditions at the surface, we would expect a material to be below its Curie point such that it is not magnetic.
     
  8. Aug 6, 2008 #7

    Evo

    User Avatar

    Staff: Mentor

    Good point, thanks for adding that.
     
  9. Aug 13, 2008 #8
    Grek.en, I think you may be onto something with the magnetic field idea and thunderstorms. It forms a useful mechanism for charge separation. Electrostatic field generation requires development of positive and negative charge realms separated by non-conducting space and the development of large voltages with later breakdown by lightning formation. Most of the motion of thunderheads is upward, but they clearly are directed across the Earth’s surface as well. The Earth’s magnetic field would favor separation of positively from negatively charged droplets in clouds. Each droplet consists of roughly a trillion water molecules. The charged elements would be about a million hydronium cations and bicarbonate anions and a substantially fewer carbonate divalent anions. Their distribution varies from droplet to droplet and the most charged droplets would migrate in the magnetic field, moving away from oppositely charged water droplets as the cloud rises and moves laterally. The rate of rise and lateral direction could play a role in the magnitude of the electrostatic charge development from the separation. You might see if the direction and speed of clouds plays a role in the magnitude of thunderstorms.

    The separation of droplets on the basis of net charge would cause repulsion of droplets from each other on an electrostatic basis and allow the 4% water content of thunder clouds to persist until intra-cloud lightning reduces some of that charge to allow raindrop formation and descent.

    You have no way to eliminate the earth’s magnetic field to test the mechanisms proposed, but indirect evidence by direction of separation should help. The magnitude of motion in the stable magnetic field should supply the energy necessary for electrostatic voltage development. Net droplet charge development could easily be seen as mediated at least in part by motion and photon activation of electrons, freeing them to migrate to another droplet or to the Earth. Electrons moved to the ground would set up an electrostatic charge causing lightning strikes to the Earth, less common than intra-cloud lightning but of more concern to our lives.
     
  10. Sep 2, 2008 #9

    gdp

    User Avatar

    No. Atmospheric electricity has no known relationship to the geomagnetic field; it is believed to be entirely the product of electrostatic processes within thunderstorms, and is basically confined to the troposphere.

    The geomagnetic field only has a significant influence on process in the ionosphere and magnetosphere. While the ionosphere serves as a conducting "roof" that terminates the electric fields and currents driven by individual thunderstorms, and it also contains a set of "ionospheric dynamo" MHD currents that are driven by the component of high-altitude winds that is perpendicular to the geomagnetic field, the ionospheric dynamo currents are not believed to contribute any energy to thunderstorm processes.
     
  11. Sep 5, 2008 #10
    gdp has claimed that charge is not meaningfully influenced by a steady magnetic field because it results in a dot product quantity https://www.physicsforums.com/showthread.php?t=252994 in which charge’s (oxygen ions) sign is lost, but the conventional treatment is that of Lorentz in which the result of motion is a cross product in which charge magnitude and sign affect direction http://en.wikibooks.org/wiki/Physics_Study_Guide/Vectors_and_scalars ,
    http://en.wikipedia.org/wiki/Lorentz_force .
    The resulting vector is influenced by the magnitude and direction of the magnetic field. The same concept may be applied to uncharged electromagnetic waves but the motion is more complex, adding rotation to photon direction. Sunspot radiation shows such behavior from the torus of magnetism that generates sunspot pairs, as shown by G E Hale at Mount Wilson and known as Hale’s laws of polarity http://web.hao.ucar.edu/public/slides/slide19.html ,
    http://www.space.gc.ca/asc/eng/sciences/sunspots2.asp .

    gdp, I agree with baywax that your discussion of the chemistry and physics of the earth’s core in https://www.physicsforums.com/showthread.php?t=249773 was brilliant. I had been thinking of introducing the concept of critical temperature to this area but have noted the use of absolute boiling point (abp) by geology sources and the incomplete understanding of chemical compound abp and compound temperature stability that limits the addition of these avenues to your model.

    Grec.en, keep looking for an effect of the Earth’s magnetic field on thunderstorms.
     
  12. Sep 5, 2008 #11

    gdp

    User Avatar

    False. I stated that a magnetic field does not in and of itself do WORK on a charged particle, because the magnetic force is identically perpendicular to a charged particle's velocity. Thus, a magnetic field can only change the direction of a charged particle's motion, not its speed --- and since kinetic energy does not depend on direction, but only on speed, the magnetic force does no WORK on a charged particle. A magnetic can only influence the energy of a charged particle indirectly, in that, when a magnetic field changes in time, by Lenz's Law a changing magnetic field induces an ELECTRIC field --- and electric fields, unlike magnetic fields, can do work on charged particle.

    ...Which is, BTW, supported by over a century of experimental data and engineering practice, so it's pretty likely to be right...

    Again I did NOT state that magnetic fields do not "meaningfully influence" charged particles. I stated that magnetic fields do no WORK on charged particles, which is a very different statement from your misrepresentation of what I claimed.

    Sorry, wrong. Magnetic fields do not change the direction of photons in any way, because Maxwell's equations are linear. Superposing an external magnetic field on an electromagentic wave does absolutely nothing to said wave.

    You are perhaps confusing the Faraday Rotation of a photon's plane of polarization when it passes through a magnetized nonlinear medium with a "rotation of photon direction." However, the Faraday effect has no affect on a photon's direction of travel, --- and even said change in polarization a property of the photon's interaction with the molecules of the magnetized medium, and is not due to any interaction of the photon with the magnetic field itself.

    First, sunspots are not "radiation," they are a magnetohydrodynamic phenomenon in the outer layers of the sun. Second, the fact that sunspots occur in oppositely polarized pairs is a trivial consequence of Maxwell's "No Monopoles" law, Div.B = 0, which implies that magnetic field lines cannot begin or end at any point, but must always form topologically closed loops.

    Thus, when motions of the plasma in the outer layers of the sun concentrate magnetic flux lines into a "bundle" or "tube" of flux, and a portion of this bundle or tube floats above the notional "surface" of the solar photosphere, the closed topology of every magnetic field-line loop necessarily requires that there must be two "spots" of opposite polarity (i.e., opposite-signed fluxes through the "surface") in the region where the flux tube rises above the photosphere.

    (Magnetic flux tubes "float" upward toward the Sun's notional surface because the interaction of a magnetic field with a plasma manifests itself as an effective "pressure" perpendicular to the flux lines, and an effective "tension" along the flux lines. The effective "pressure" perpendicular to the flux lines partially excludes plasma from the interior of the flux tube, reducing its density, and therefore making it more "buoyant" than the surrounding plasma. Once a portion of the flux tube has "floated" above the "surface" of the photosphere, the enhanced transport of particle thermal energy along the field lines and suppressed thermal transport perpendicular to the field lines causes the plasma in the tube to cool off relative to the surrounding plasma, causing it to look "darker" by comparison to the surrounding plasma --- although even sunspot plasma is still hotter and brighter per unit area than the hottest tungsten lightbulb filament!)
     
    Last edited: Sep 5, 2008
  13. Sep 9, 2008 #12
    I recommend that gdp study the offered citations before responding so quickly. The Wikibooks article develops application of the right hand rule to Lorentz forces. The Wikipedia article clearly shows that movement orthogonal to a magnetic field will act to separate charged particles and generate an electrostatic field. Near longitudinal and vertical motions qualify. The historical Lord Kelvin alternative depends on already present electrostatic charge. http://www.eskimo.com/~billb/emotor/kelvin.html
    http://www.eskimo.com/~billb/emotor/ikelv.html

    I took my first college physics course from the late Felix Bloch, who later won the Nobel prize for his work on nuclear magnetic behavior. http://nobelprize.org/nobel_prizes/physics/laureates/1952/bloch-lecture.pdf One day after class, I asked him about the potential of bimetallic surfaces to generate electric currents when exposed to light photons, then recently observed. He dismissed the idea as impractical. That idea has led us to all of our solar power discoveries. I learned from this experience to be less dismissive of unexpected ideas.

    I will take a few days to add to the Hale discussion. It offers a lesson in funding as well as being historically important to astrophysics.
     
  14. Sep 9, 2008 #13

    LURCH

    User Avatar
    Science Advisor

    I'm always a bit wary when someone tries to make a distinction between a change in speed and a change in direction. Either way, if the magnetic field changes the direction of a particle, has it not caused an acceleration? If it has caused an acceleration, has it not done work?
     
  15. Sep 9, 2008 #14

    LURCH

    User Avatar
    Science Advisor

    Also;
    I have heard this explanation of lightning formation many times, but I have also heard it said that we really don't know exactly how lightning is formed. What especially intrigues me is this process of charge being built up as a result of the collisions of ice crystals. Has anyone ever recreated lightning this way in a laborotory environment? Or, has anyone at least generated a charge this way?
     
  16. Sep 9, 2008 #15

    gdp

    User Avatar

    So what? The energy for your electric field is coming from the kinetic energies of the charged particles, and NOT from the static magnetic field itself. According to over 100 years of experimental evidence, a static magnetic field cannot in, of, and by itself do any net work on charged particles.

    ...And since almost no body will ever be perfectly electrically neutral, and since the Kelvin process leads to an initially exponentially growing charge-separation as long as there is any initial imbalance at all, it is entirely capable of explaining the observed thunderstorm electrification, without resort to any speculative new physics involving non-lorentzian static magnetic forces that somehow do work, in violation of the experimental evidence to the contrary.

    Irrelevant red-herring argument. And please note that there is such a thing as being so "open-minded" that your brains fall out.

    If you have experimentally reproducible evidence that the lorentz force has been experimentally falsified, and that a static magnetic field can indeed do net work on a charged particle, the post it or a reference to it. However, "you should be more open-minded --- who knows, the lorentz force just might be wrong, despite 100 years of experimental evidence to the contrary" is NOT a scientifically or logically valid argument.
     
  17. Sep 9, 2008 #16

    gdp

    User Avatar

    Why? speed is a directionless non-negative scalar, while velocity is a is a three-dimensional, directed vector. Speed and velocity are physically distinct quantities.

    No, it has not. Since the kinetic energy --- a scalar quantity! --- is the same after a pure change in direction with no change in speed, no net work has been done by the external force.

    If a force had done net work while changing the direction of the particle without changing its speed, it would violate the Law of Conservation of Energy: It's not in the particle, and its been lost by the force-producing agent, so where would the work have gone? Has it vanished into the Aether?

    If forces could do work by changing a particle's direction without changing its speed, then nearly all of physics as we know it would have had to have been wrong; we would have to scrap everything all the way back to Newton, and start over from scratch. Does it really seem plausible to you that over 300 years worth of physical experiments are wrong, and that nearly all the conclusions drawn from those experiments and the theory developed from those conclusions are falsified?

    [Part of your conceptual problem may be that you may emotionally feel as if your muscles are "doing work" even when exerting a static force, or perhaps you cannot imagine that a chair can hold you off the floor without somehow "doing work." However, in the first case, the "work" is actually being wasted as heat dissipated inside your muscles due to their internal inefficiency --- the molecular motors inside your muscle fibers are constantly grabbing and pulling, then releasing and sliding back, and then grabbing and pulling again, wasting energy during every cycle --- while the "work" done by a chair is a conservative force: Any work done by the chair when you compress its physical structure by sitting on it will be released again when you get off of it --- and no work at all is done while you are sitting on it.]
     
  18. Sep 9, 2008 #17

    gdp

    User Avatar

    Sure. To find out about generation of charge separation by friction or impact, google on triboelectricity. You separate charges by this process every time you scuff your feet across a carpet.

    And you can easily build a device that generates electric sparks of quite respectable voltages using the splitting-off of falling water droplets called a Kelvin Generator out of two tin cans, two lengths of stiff wire, two short lengths of metal tubing, after just a bit of soldering.
     
  19. Sep 10, 2008 #18

    LURCH

    User Avatar
    Science Advisor

    But speed and direction are not. The difference between them is frame-dependant. What one observer calls a "change in speed," another can call a "change in direction." But regardless of one's frame, a change in speed or a change in direction is a change in velocity. And a change in velocity is an acceleration, which is work.
     
  20. Sep 10, 2008 #19

    gdp

    User Avatar

    I'm sorry, but you are confusing a passive change of inertial frame of reference with an active change in some particle's velocity when it is acted upon by some external force; however, these two concepts are again physically quite distinct. The former is just a passive relabeling of spacetime points, and it does nothing "physical;" in particular, no new "forces" act on any particle if one arbitrarily selects a new inertial frame of reference, and no "work" is done on anything by arbitrarily selecting a new inertial frame of reference.

    The latter, an active acceleration of a particle by an external force does involve a force by definition, and may do work if said active force vector has a component parallel to said particle's velocity vector.

    You can't make a measurement of velocity in one inertial reference frame A, change reference frames to another inertial frame Z, then make a second measurement of velocity, and claim that an "acceleration" has occurred between the two measurements, because by doing so you are trying to compare apples to zucchini (velocity relative to inertial frame A with velocity relative to inertial frame Z). Measurements may only be physically compared when all of the measurements have been taken IN THE SAME INERTIAL FRAME, notwithstanding whether you are working from Newton's Principia or Einstein's Special Relativity.

    Furthermore, to return to the original contrafactual claim that a static magnetic field can somehow "do work," by dragging in a second inertial reference frame, you're no longer talking about just a "pure" magnetic field, because a magnetic field will appear as a magnetic field plus an electric field if you boost crosswise to the original "pure" magnetic field's direction. And electric fields do do work.

    Finally, don't muddy the water further by trying to drag General Relativity into it, because things will only get worse: Inertial frames don't even exist in General Relativity, except in the limit of "local tangent frames" which are infinitesimal in spacetime extent --- so in GR you can't even compare two velocities at all any more, unless two particle's worldlines' just happen to both pass through the same spacetime event (i.e., you can't compare the relative velocities of anything in GR, except when they collide with each other!).
     
    Last edited: Sep 10, 2008
  21. Sep 12, 2008 #20

    LURCH

    User Avatar
    Science Advisor

    Absolutely not. I'm saying that a change in speed or direction is a change in velocity, and therefore an acceleration.
    But your final conclusion is that particle with mass can change direction without any acceleration, is this true or false?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Lightning connected with the magnetism of Earth core?
  1. The Earth's core (Replies: 6)

  2. The core of the earth (Replies: 24)

Loading...