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Thread: tidal friction

  1. #1 tidal friction 
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    Does anyone know how much energy/heat is generated with in the Earth by tidal friction ? The earth/moon system rotates around a common center point which is located in a path some thousands of miles from the center of the earth but well below the surface of the planet. The Earth however rotates around its axis. This has to generate fluid friction in the outer core of the earth. This fluid friction has to generate heat. Yet everything I read about sources of geothermal heat ignors this source. What am I missing?


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    I found this ...... Curious About Astronomy: Is Earth-moon tidal friction causing global warming?
    and this .....http://ocean.stanford.edu/gp141/papers/Egbert.pdf

    So it looks as though there must be some regular, in fact constant, ocean warming and transfers of energy within the oceans as a result of these processes. But if you want a link to recent warming, you'd need some mechanism or explanation for how this process has changed to release more energy into the oceans during the last couple of centuries. I found a few that discussed how these mechanisms affect the rotations of earth and moon and the consequences for increasing the distance between them, but nothing that I could see about recent changes.


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    Thanks, but I'm thinking of energy generated by the plastic deformation of Earth's outer core and mantle rock, not the movement of oceans. Plastic deformation generates heat. That's why radial tires last longer than bias corded tires, they have softer, thiner side walls and so resist deformation less and in turn generate less heat in the side wall of the tire. It is the heat that causes the rubber to breakdown leading to tire failure. The heat within the Earth drives tectonic movement and volcanism but the heat is not adequately explained by other mechanisms.

    I suspect that the presence of a large moon that generates internal tidal stress within the parent planet may be required to power tectonic movement and volcanism which in turn strongly influence atmospher generation. In the long term this impacts the search for extra solar, earth like, planets. The target world may need not only to be in the "golilocks zone" but also be part of a pair of nearly equal co orbiting bodies.

    Apparently there are a lot more planets out there than stars but not many of them are in the "golilocks zone" and still fewer have big moons. If a big moon is a necessary precurser to the development of life then this thins the field of possible life bearing worlds and at the same time makes them easier to spot.

    I know there are a lot of "ifs" in that speculation but its only fair to explain where I'm going with this.
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  5. #4  
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    Quote Originally Posted by Sealeaf View Post
    If a big moon is a necessary precurser to the development of life then this thins the field of possible life bearing worlds and at the same time makes them easier to spot.
    Earth May Not Have Needed Moon for Life : Discovery News
    Why Earth may not have needed a moon for life to exist | Mail Online
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  6. #5  
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    Thanks, but I'm thinking of energy generated by the plastic deformation of Earth's outer core and mantle rock, not the movement of oceans.&nbsp; Plastic deformation generates heat.&nbsp; That's why radial tires last longer than bias corded tires, they have softer, thiner side walls and so resist deformation less and in turn generate less heat in the side wall of the tire.&nbsp; It is the heat that causes the rubber to breakdown leading to tire failure.&nbsp; The heat within the Earth drives tectonic movement and volcanism but the heat is not adequately explained by other mechanisms.&nbsp;&nbsp;<BR><BR> I suspect that the presence of a large moon that generates internal tidal stress within the parent planet&nbsp;may be required to power tectonic movement and volcanism which in turn strongly influence atmospher generation.&nbsp; In the long term this impacts the search for extra solar, earth like, planets.&nbsp; The target world may need not only to be in the "golilocks zone" but also be part of a pair of nearly equal co orbiting bodies.&nbsp; <BR><BR>Apparently there are a lot more planets out there than stars but not many of them are in the "golilocks zone" and still fewer have big moons.&nbsp; If a big moon is a necessary precurser to the development of life then this thins the field of possible life bearing worlds and at the same time makes them easier to spot.<BR><BR>I know there are a lot of "ifs" in that speculation but its only fair to explain where I'm going with this.
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    Oh, OK. Didn't see anything along those lines either I'm afraid. Maybe the NASA site? (I've given up searching there - I never seem to get what I want unless I've been given a direct link or a hold-my-hand-as-I-go map.)
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    Hm, you gave me some thought there.

    But let's be fair. The most and best we can view the mantle is like a viscous fluid with some magnetic properties. It is still however a fluid. And normally this doesn't do that much but I think that the heat, if it is generated at all, will find itself mostly into pressure differences then into temperature. As that is already high but more importantly, not 'too' high. I can easily double the heat of a plasma without it suffering to much changes in this pressure. But the change of pressure is a lot more difficult due to the massive pressure already present. It could store the energy locally in phase transformations of some sort.
    If the heat matters, it will probably be trapped by phase changes and then later released. In effect the reason probably no body ever written about it, is because the effects are too small to be noticed due to the 'pressure buffering' as described above.
    I can however imagine this being a large effect in planets without a liquid mantle. But on earth? No, don't think it is measurable.
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    It is possible, perhaps tidal forces is what can cause different magma flow in the earths cores, which would explain the differences of magnetic poles. I wonder if there are phases where the potential reaches a maximum and then you have a violent status quo event all induced by the Earth-Moon barycentre.
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    Does tidal heating have an effect of the core temperature of the Earth? - Yahoo! UK & Ireland Answers

    while the source may not appear the best the answer "looks" ok. it will give you another avenue to explore anyway.
    Sometimes it is better not knowing than having an answer that may be wrong.
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  11. #10  
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    Quote Originally Posted by Sealeaf View Post
    Thanks, but I'm thinking of energy generated by the plastic deformation of Earth's outer core and mantle rock, not the movement of oceans.&nbsp; Plastic deformation generates heat.&nbsp; That's why radial tires last longer than bias corded tires, they have softer, thiner side walls and so resist deformation less and in turn generate less heat in the side wall of the tire.&nbsp; It is the heat that causes the rubber to breakdown leading to tire failure.&nbsp; The heat within the Earth drives tectonic movement and volcanism but the heat is not adequately explained by other mechanisms.&nbsp;&nbsp;<BR><BR> I suspect that the presence of a large moon that generates internal tidal stress within the parent planet&nbsp;may be required to power tectonic movement and volcanism which in turn strongly influence atmospher generation.&nbsp; In the long term this impacts the search for extra solar, earth like, planets.&nbsp; The target world may need not only to be in the "golilocks zone" but also be part of a pair of nearly equal co orbiting bodies.&nbsp; <BR><BR>Apparently there are a lot more planets out there than stars but not many of them are in the "golilocks zone" and still fewer have big moons.&nbsp; If a big moon is a necessary precurser to the development of life then this thins the field of possible life bearing worlds and at the same time makes them easier to spot.<BR><BR>I know there are a lot of "ifs" in that speculation but its only fair to explain where I'm going with this.


    Here's the thing, that 3 Tw the article talks about is most of the energy available for tidal heating. What you do is take the energy gained by the moon and the rotational energy lost by the Earth and take the difference. This give ~3.7 Tw total energy available for tidal heating. If the oceans take up 3 Tw, that leaves only 0.7 Tw left over for the crust and mantle. Now considering that the 3 Tw distributed among the oceans does not heat them up enough to contribute to global warming, then 0.7 Tw distributed among the much larger mass of the mantle won't either.
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