Panama canal: why don't the two sides level out?

  1. The sea level is different from one side of the Panama canal to the other. The pacific side is 20 cm higher.

    Why don't the levels equalize by water flowing around south america?
     
  2. jcsd
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  3. Born2bwire

    Born2bwire 1,776
    Science Advisor
    Gold Member

    Because of the locks. They only let enough water flow in/out to raise/lower the ship inside each lock. In such a way, they do not allow for a continuous flow of water between the two oceans but only small intervals of water.
     
  4. Cleonis

    Cleonis 691
    Gold Member

    If there would not be any ocean currents at all then indeed it would not be possible for any level difference to exist, since by nature water forms a level surface.

    I suppose that the 20 cm difference arises because of prevailing ocean currents. Presumably at each side of the Panama canal the ocean currents come out in such a way that difference in level arises.
     
  5. Shouldn't the levels fluctuate seasonally if they were due to ocean currents?

    By the way Born2bwire the locks are to carry ships over a mountainous area that is higher than both oceans, and also I asked why doesn't water go all around south america to equalize.
     
  6. Cleonis

    Cleonis 691
    Gold Member

    I think the major ocean currents are pretty consistent all throught the seasons.

    The driving force is that around the equator the water is heated more than at higher latitudes. That differential heating tends to cause a circulation where surface water flows away from the equator, and deep water flowing back. The Earth's rotation tends to redirect that flow (coriolis effect), and geographic features also tend to redirect.

    In all the ocean currents are determined more by geographic features than by seasonal features.
     
  7. The Pacific Ocean is 20cm higher than the Atlantic. Not just through the canal.

    This answers your question perfectly:

    http://www.psmsl.org/train_and_info/faqs/#3
     
  8. So if we go to a long lake and disolve a lot of salt on one side of the lake, the opposite side will rise?
     
  9. If you dissolve a lot of salt the densities change so you'd expect some variation.

    Also re-read what is in the link relating to gravity.
     
  10. Cleonis

    Cleonis 691
    Gold Member

    Let me propose another setup.
    Let there be two lakes, close to each other but not connected. Let the two lakes have the same level, and the same depth. Dissolve a lot of salt in one of the lakes, then establish a conduit between the bottoms of the two lakes (say, a water filled pipe.)

    With that setup I expect that water will move through the conduit from the higher density lake to the lower density lake. The equilibrium point will be the point where the pressures at the two sides of the conduit are equalized.

    So I think it's a case of communicating vessels, with a bias due to the density difference.
     
  11. Shouldn't the two densities have equalized by now? It's been billions of years.
     
  12. Only if there were no changes (no salt added or removed, weather and currents etc). But unfortunately, nature isn't that simple.
     
  13. Maybe because there are more rivers flowing to the atlantic than to the pacific, per cubic foot of sea water?
     
  14. What?

    Are you not reading what's been posted above?

    I gave you the exact reasons why the Pacific is higher than the Atlantic. There's really no more to it.
     
  15. You said changes prevent density equalization and therefore cause the difference in level. But changes happen on both sides. Currents too flow on both sides and seem completely unconnected. Are you yourself satisfied that currents cause one side to be heavier?
     
    Last edited: Feb 20, 2011
  16. What are you talking about? Stop making things up.

    Please read my initial post in this thread. I quoted you an entire section of a site explaining exactly why the ocean levels are different.

    I have never said the differing levels prevent density equalisation. Ever.

    EDIT: Your edit noted.
     
    Last edited: Feb 20, 2011
  17. Look at your #11 post:
    - Shouldn't the two densities have equalized by now? It's been billions of years.
    - Only if there were no changes.

    What did you mean then, if not that changes lead to no equalization of density?
     
  18. RE. Bolded: That is exactly what I meant, but that isn't what you wrote.

    The salt levels would only have equalised if there was no further input / removal of salt, among other things. This is not how nature works.

    Again, I have never said the different levels prevents the salt level equalising.

    There are changes in nature, salt is constantly added and removed alongside other factors that prevent the levels equalising.

    Please read the link I provided, it explains it perfectly well.

    I don't know if there's a language barrier here or not, but you aren't reading what I write correctly. As such, you are posting what amounts to non-sense based on what I've never said.
     
  19. Good. You mean that changes lead to no equalization of density and you agree that no equalization of density leads to differing levels, correct?

    In other words, A leads to B and B leads to C, does it not follow that A leads to C? In other words, that changes lead to differing levels? You do not say it word for word, but you say the equivalent.

    But since there is further input / removal of salt, one has to be denser, which is like saying

    "if you input food to two childen, one will be fatter".

    Well I suggested that one child seems to be fed more food. One ocean receives more salt. Where from? More rivers.

    I have read it since the first time you gave it, and copy-pasted it. It does not account for a difference in density. It does not answer why SALT does not diffuse around south america to equalize densities.

    You proposed that salt content does not equalize because, word for word, "only if there were no changes (no salt added or removed, weather and currents etc) [would the densities have equalized]. Well consider that salt is added to both sides, weather is similar on both sides, and only currents are perhaps one-sided in a salt-obstructing effect. But currents go in closed paths don't they? How can they obstruct diffusion?
     
    Last edited: Feb 20, 2011
  20. Rivers are fresh water, so how would the ocean get salt from them?

    You enjoy closed systems don't you. I've read your other threads and it's a general theme.

    Currents aren't "closed paths".

    It is the continual processes occurring in both oceans, along with other factors (gravitational variation), that prevent them from equalising.
     
  21. Good, then that is a strong indicator that salts should distribute themselves worldwide, is it not?
     
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