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Author Topic: Can Water Run Uphill?  (Read 4391 times)

Offline CliffordK

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Can Water Run Uphill?
« on: 12/05/2011 21:28:56 »
I was doing a thought experiment today.  Yes, I know that is dangerous!!!!



From the chart above, the bottom tube is dependent on mass.
So, with it open, different temperatures in the two flasks will lead to different levels in the flasks.

The top tube is dependent on water level, and will tend towards equalizing the two levels.

Open both valves, and one gets a circular flow of water. 

Levels will eventually reach an equilibrium with different levels between A & B, but somewhere in the middle with A somewhat higher than B.  The circular flow will continue as long as the temperature gradient exists because the top tube will have flow due to the different levels, and always will try to return to equal levels between the flasks.  The bottom tube will try to maintain equal masses, and will compensate.

So.
Why did I put this under Environment?
I've been trying to figure out how temperature can affect sea levels.

In particular with the Western Pacific Ocean having much lower sea levels and sea level rise than the Eastern Pacific Ocean.

http://climate.nasa.gov/blogs/index.cfm?FuseAction=ShowBlog&NewsID=239


Initially, one would expect that the water to run downhill...  and eventually equalize the levels.

However, as noted by my flask thought experiment above.  The "mass effect" will cause the Eastern Pacific to have a higher sea level than the Western Pacific if there is a temperature gradient with more warming in the Eastern Pacific than the Western Pacific.


 

Offline RD

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« Reply #1 on: 13/05/2011 00:14:38 »
There is convection in the ocean.
 

Offline CliffordK

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Can Water Run Uphill?
« Reply #2 on: 13/05/2011 00:32:20 »
Ahh.
So the density gradient from thermal expansion drives convection, essentially what I demonstrated would be possible with 2 flasks.

And...  the density gradient can also allow for different sea levels.
 

Offline Geezer

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« Reply #3 on: 13/05/2011 17:46:04 »
I seem to remember systems have been proposed that would extract power from the thermal gradient, although I don't exatly remember how they were supposed to work  :D
 

Offline frethack

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Can Water Run Uphill?
« Reply #4 on: 13/05/2011 19:21:52 »
The Eastern Pacific sea level is not always significantly higher than the Western Pacific...mostly during La Nina events.  The easterly trade winds are much stronger over the equatorial pacific during a La Nina, which equates to stronger surface currents and a pile up of warm water in the Western Pacific Warm Pool.  During a strong El Nino, the equatorial surface currents reverse (because of a reverse in the atmospheric Walker Circulation), and pile warm water into the Eastern Pacific.

The sea level difference, in large part, is dependent on the wind strength and direction of the Pacific ITCZ.
 

Offline CliffordK

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Can Water Run Uphill?
« Reply #5 on: 14/05/2011 01:38:06 »
The Eastern Pacific sea level is not always significantly higher than the Western Pacific...mostly during La Nina events.  The easterly trade winds are much stronger over the equatorial pacific during a La Nina, which equates to stronger surface currents and a pile up of warm water in the Western Pacific Warm Pool.  During a strong El Nino, the equatorial surface currents reverse (because of a reverse in the atmospheric Walker Circulation), and pile warm water into the Eastern Pacific
I had wondered about that.

I'm just not finding any sea surface height anomaly maps that indicate lower sea surface heights in the Eastern Pacific this decade.

This covers from May 2010 (late El Nino cycle) to April 2011 (mid La Nina cycle)
http://www7320.nrlssc.navy.mil/global_ncom/anims/glb/ssh12m.gif

Everything else I find seems to indicate a significantly higher rate of sea level change in the Eastern Pacific than the Western Pacific too.  See above for 2008.

Some of it may be because of tectonic activity.  But, it is odd.

Or, perhaps the baseline is off.
 

Offline yor_on

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Can Water Run Uphill?
« Reply #6 on: 14/05/2011 05:27:55 »
The oceans are a mix of streams at different strata (depths), some colder some warmer and they all keep together, also you may have a different salinity in those streams. I'm sure they all mix to some degree, but they also keep apart. Then you have the idea of the biological mass (fish etc) mixing the water as they swim, as well as under-water volcanoes, winds, rain etc.

To me it seems phreakin complicated Clifford :) Also, our knowledge of how the ocean works isn't that perfect, our probes are relatively few as I understands it. So there could be more effects.
 

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Can Water Run Uphill?
« Reply #6 on: 14/05/2011 05:27:55 »

 

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