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stedwards
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1) Is there any evidence that the Earth's magnetic field originates in the core rather than elsewhere?
2) Is there a compelling physical model?
2) Is there a compelling physical model?
What, you mean like Cincinnati?stedwards said:1) Is there any evidence that the Earth's magnetic field originates in the core rather than elsewhere?
2) Is there a compelling physical model?
SteamKing said:
I got the impression he was asking "where" Cincinatti was, as a humorous riposte to that portion of Steam King's post.SteamKing said:If you don't want to read the links, no one can help you.
Ophiolite said:I got the impression he was asking "where" Cincinatti was, as a humorous riposte to that portion of Steam King's post.
Here I am!stedwards said:Anyone else without an axe to grind?
Ophiolite said:Here I am!
But seriously stedwards, perhaps the misunderstanding could have been avoided if you had indicated in your OP that you were knowledgeable about the topic and had some specific reservations you wanted to discuss. As it was, others - myself included, thought the post was from a neophyte who was either too lazy, or too unskilled to do some basic searches.
In the light of your actual position and before we address shortfalls of current theory, it seems you have a notion the field originates somewhere other than the core. Is that correct, and if so where? And how? And are we allowed to discuss alternative theories inside the main fora?
Here is some, really very little, experimental evidence that Earth's magnetic field originated elsewhere, and is merely amplified with the core.stedwards said:1) Is there any evidence that the Earth's magnetic field originates in the core rather than elsewhere?
2) Is there a compelling physical model?
www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Magnetic_complexity_begins_to_untangle
Swarm is tasked with measuring and untangling the different magnetic signals that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere – an undertaking that will take at least four years to complete.
In doing so, the mission will provide insight into many natural processes, from those occurring deep inside the planet through to weather in space caused by solar activity. In turn, this information will yield a better understanding of why the magnetic field is weakening.
jim hardy said:If one takes a thin spherical shell of charge and sets it into rotation
does a magnetic field result ?
Apparently it does
What happens if, as in a simplified Earth's atmosphere
two concentric spherical shells of charge are separated by 50 km
and there's an E-field between the shells , Earth's is a few hundred volts per meter
and the shells rotate rotate in lockstep
1. Does a magnetic field result?
2. Is it in same direction as Earth's?
might there be more going on up there than we think?
stedwards said:Upwelling matter from the core is (quazi-) organized into rotating structures called Tylor Columns due to coriolis force.
Alisdair said:Really nice post Jim.
I had a look at those links you posted and pretty quickly found myself out of my depth... but as you're a smart cookie and appear to have time on your hands enough to post here I thought I'd ask...
Alisdair said:Food for thought...
Are there connections between the Earth's magnetic field and climate? https://www.researchgate.net/publication/222817231_Are_there_connections_between_the_Earth's_magnetic_field_and_climate
I think it a mistake to think of the core as an immediate field generator. The Earth must contain a historical collection of magnetic fields, interlocked with circulating electric currents, on and in the conductive core. It takes a long time for things that big and conductive to change. Even if it did not generate the field, the core would be a good place to store a field. I think we need to keep an open mind rather than hang our hat on anyone simple theory.jim hardy said:everybody seems to look inside not outside.
We can try to apply magnetohydrodynamics (MHD) to the atmosphere.jim hardy said:What happens if, as in a simplified Earth's atmosphere
two concentric spherical shells of charge are separated by 50 km
and there's an E-field between the shells , Earth's is a few hundred volts per meter
and the shells rotate rotate in lockstep
1. Does a magnetic field result?
2. Is it in same direction as Earth's?
I do not expect Earth's magnetic field to be induced and accumulated in the core by the motion of atmospheric charge, but it is certainly coupled to some extent.jim hardy said:might there be more going on up there than we think?
You're welcome Jim and thanks for the links. It'll take me a while to get through that lot.jim hardy said:Thanks for the kind words Alisdair...
...if you find a page for those satellites watching Earth's magnetic field please post link.
old jim
Baluncore said:Atmospheric mass redistribution result in very slight annual changes to the speed of rotation of the Earth. The seasonal variational in the mass of snowfall is part of that process. Most ice in the Arctic is floating so it makes little difference to the mass distribution. Longer term changes in the Antarctic or Greenland icecaps may result in a slight axial change but it is not going to do much to the magnetic field from the core.
I do not expect Earth's magnetic field to be induced and accumulated in the core by the motion of atmospheric charge, but it is certainly coupled to some extent.
Yes, there is more going on than is admitted in the simple theories. This is a field of science that is ripe for exploration.
I do not believe that is the case. I believe that the atmosphere is effected by the magnetic field.Alisdair said:I really like your idea about an atmospherically generated gmf.
The coriolis force is massive compared with the few milliseconds variation in the length of a year. It will swamp the variation.Alisdair said:With regards the slight changes in Earth's orientation or speed change or similar I was thinking along the lines of the resultant Coriolis Force and how this might affect outer core liquid metal flow and in turn, magnetic field lines.
No. The Earth spins on its axis that passes through it's centre of mass. There is no wobble that could be amplified by rotation.Alisdair said:Would magnetic field lines move if this wobble caused anomalous Coriolis Force which then induced a temporary and minute change in the flow direction of the liquid metal in the outer core? Could then repeated wobbles with corresponding changes in direction flow create a geomagnetic excursion?
The tidal effects of the Moon and Sun effect the Earth's figure as well as the water on the surface. Distortion of the Earth by about one meter at the surface is unlikely to have any effect on the core or the magnetic field. Planets will have no effect whatsoever.Alisdair said:Could motion of other planetary bodies and the moon, in immediate proximity, have a gravitational effect on the liquid metal outer core and induce minor changes in flow direction which result in an excursion? Could these then fluctuate based on the proximity of other planets?
I do not believe the atmosphere generates the field. What have the oceans got to do with it?Alisdair said:Alternatively, with Baluncore's idea on atmospheric gmf generation could the same impacts be felt on the atmosphere the same way they're undergone by the oceans?
Baluncore said:I do not expect Earth's magnetic field to be induced and accumulated in the core by the motion of atmospheric charge, but it is certainly coupled to some extent.
Alisdair said:I really like your idea about an atmospherically generated gmf.
stedwards said:Take a cylinder of iron and spin it about its axis and it does not generate a magnetic field, obviously.
Dotini said:
According to the following resource, about 10% of Earth's surface magnetic field is is due to atmospheric processes.
http://www.albany.edu/faculty/rgk/atm101/magnet.htm
...about 10% of the surface magnetic field is due to processes in Earth's atmosphere. This contribution is called the External Field.
I believe that is referring to the upper atmosphere and ionosphere, where solar radiation and ions react with the thin gas of the upper atmosphere.Dotini said:However, about 10% of the surface magnetic field is due to processes in Earth's atmosphere. This contribution is called the External Field.
You need to think about it for longer than a minute. Try starting with a whole year of active research.Dotini said:Thinking about this process for just a minute:
The trade winds flow at the surface and are very reliable. They have a seasonal variation but little daily variation. The mass of that much atmosphere is very difficult to speed up or slow down.Dotini said:As night turns to day, a gentle trade wind blows east to west.
There are four jet streams driven by Earth rotation, not by diurnal effects. http://virga.sfsu.edu/pub/jetstream/Dotini said:As day turns to night, a stronger jet stream wind blows west to east.
As the original quote said; a substantial 10% is due to atmospheric effects. Are you suggesting that those effects are somehow built up and accumulated deep in the body of the Earth?Dotini said:So maybe the Earth's magnetic field could be partly or even substantially generated by the atmosphere after all.
Energy in the atmosphere comes from solar radiation and Earth rotation. If the atmosphere circulation is principaly driven by rotation then it will slow Earth down rather than speed it up.Dotini said:And maybe even the spin of the Earth is helped along or even maintained by the lateral gradient of the electric field and the blowing of the prevailing wind.
Yes. And that field will be about 10% of the total.Dotini said:So an electric current will flow in the atmosphere around the Earth.
And a magnetic field will be generated orthogonal to the current.
Baluncore said:Simply put, there is a magnetic field from a N magnet pole in the Antarctic where the penguins are, to a S magnet pole in the Arctic where the bears are. (Remember that a North magnet pole is one that seeks the North of the Earth, so the Earth's Arctic must actually be a S magnet pole).
The charged Earth–Ionosphere capacitor rotates with the Earth. I would expect the charges on the two spherical electrodes to be equal and opposite, so the magnetic effects should significantly cancel.jim hardy said:...
... eight or nine orders of magnitude too small .
I don't think that's the source.
Baluncore said:That would require a reversal of the polarity of charge on the Earth.
Baluncore said:See if you can find a diurnal effect in these streams.
Yes. If they get here a couple of days later, protons and electrons in the solar wind are sorted differently by the Earth's magnetic field. That distorts the field during magnetic storms.jim hardy said:Do CME's transport charge ?
Atmospheric and ionospheric electric effects; YES. They are due to exposure to sunlight and the solar wind.Dotini said:I found a diurnal effect in the electric field.
Atmospheric circulation velocity; NO variation.Dotini said:As night turns to day, a gentle trade wind blows east to west.
As day turns to night, a stronger jet stream wind blows west to east.
The Earth's magnetic field is created by the movement of molten iron and nickel in the outer core of the planet. This movement, known as convection, generates electric currents which in turn create the magnetic field.
The Earth's magnetic field acts as a shield, deflecting harmful charged particles from the sun and cosmic rays from reaching the surface of the planet. This protection is crucial for maintaining life on Earth.
Yes, the Earth's magnetic field is not constant and can change in strength and direction over time. In fact, the magnetic poles have reversed multiple times in the Earth's history. However, it is unlikely that the magnetic field will disappear completely as it is constantly being replenished by the Earth's core.
Scientists use a variety of tools and techniques to study the Earth's magnetic field. This includes magnetic field measurements from satellites, ground-based observatories, and even rocks and sediments that record the Earth's magnetic history.
Yes, the Earth's magnetic field has a significant impact on our daily lives. It is essential for navigation, as compasses use the magnetic field to point towards the North Pole. It also plays a role in the migration patterns of animals and the functioning of some electronic devices.