What Are Love Numbers and How Do They Impact Tidal Deformations?

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SUMMARY

The discussion focuses on the concept of Love numbers and their impact on tidal deformations, particularly in relation to the Earth's rotation and the Moon's gravitational influence. Participants clarify that the Earth's rotation is slowing due to tidal friction caused by the Moon's gravitational pull on Earth's tidal bulges. Additionally, it is established that tidal interactions occur in various Earth layers, including the atmosphere and mantle, but not in 100% rigid bodies, as they cannot produce tidal bulges. The conversation highlights the importance of understanding these interactions for comprehending tidal dynamics.

PREREQUISITES
  • Understanding of tidal mechanics and gravitational interactions
  • Familiarity with the concept of tidal friction
  • Knowledge of Earth's rotational dynamics
  • Basic principles of Love numbers in geophysics
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  • Research "Love numbers and tidal deformations" for a deeper understanding of their significance
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  • Investigate "tidal interactions in different Earth layers" for insights into atmospheric and mantle effects
  • Study "the role of rigidity in tidal dynamics" to understand limitations of solid bodies in tidal interactions
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Geophysicists, oceanographers, and anyone interested in the dynamics of tidal forces and their effects on planetary bodies.

Hoophy
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So I THINK I understand that the tidal bulge is resting slightly in front of the moon because of the Earths rotation and the moons gravity, it pulls the moon 'forward' a little adding energy to the moons orbit and expanding it, what I do not understand is why the Earths rotation is slowing. I think I understand that it the energy of the tides (And also tidal electricity generation) has to come from somewhere. Could somebody please explain to me why mechanically the Earth's orbit slows down? Also do these tidal interactions occur with the atmosphere and mantle? Can these tidal interactions occur between hypothetical 100% solid bodies, if so to what extent? Also if my original assumptions are wrong please let me know, as I know you will. Thank you for your time. :)
 
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Last I heard, the Earth's rotation was speeding up. This was due to dams holding large bodies of water at high latitudes, thus bringing more of the Earth's mass towards the center.
 
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The moon has a braking effect on Earth's rotation due to tidal friction. This also causes the moon to slowly recede from the earth. It will eventually become tidally locked with earth, but, probably not before the sun incinerates it.
 
Algr said:
Last I heard, the Earth's rotation was speeding up. This was due to dams holding large bodies of water at high latitudes, thus bringing more of the Earth's mass towards the center.

dunno where you heard that, but it is incorrect

if what you said was true, we would be taking away leap seconds, not adding them periodicallyDave
 
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Hoophy said:
Could somebody please explain to me why mechanically the Earth's orbit slows down?

The Moon's gravity pulls on the bulges, and the bulges pull on the rest of the Earth. So as the Moon is pulled forward by the leading bulge, the Earth is pulled in the opposite direction, which slows its rotation down.

Hoophy said:
Also do these tidal interactions occur with the atmosphere and mantle?

I'm sure the atmosphere is pulled just like the tides are, it's just that any effect would be much smaller than the tides. As for the mantle, I don't know.

Hoophy said:
Can these tidal interactions occur between hypothetical 100% solid bodies, if so to what extent?

If you mean 100% rigid bodies, then I don't believe so.
 
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There are also tides in the solid part of Earth. The LHC at CERN has to adjust their magnets frequently because the ring geometry changes due to those tides. On a global scale, the Earth is not that solid.
LHC and tides
 
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Here's a pic from a random website showing the interaction Drakkith described:
tidalbraking.jpe


Regarding effects of rigidity on tidal deformations, you might want to look at 'Love numbers'. Googling for the phrase is slightly problematic, for obvious reasons - just make sure you add the keyword 'tides' to your search query.
In short, you don't get tidal braking from a 100% rigid solid, as the tidal potential can't produce a tidal bulge. Since such a thing doesn't exists in reality, you end up with varying degrees of tidal interactions depending on composition - the atmosphere responds differently than the oceans, which differ from the crust, which differ from deeper, denser regions of the planet.
 
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