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Old 20 March 2007, 02:31 AM
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Silas Sparkhammer Silas Sparkhammer is offline
 
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Whalephant Mississippi River Runs Uphill: Coriolis Force

I'd never heard this'n before: my brother-in-law said that he had heard or read somewhere (couldn't remember where) that the southernmost portion of the Mississippi River (maybe the last 1/3 of the river) is actually running uphill, but it is impelled southward by Coriolis Force, which makes up for it actually gaining elevation.

The story may be relying on the earth's equatorial bulge, and on "centrifugal force" (not Coriolis) in which case, hm.... Is, say, the river level at New Orleans farther from the center of the earth than the river level at Vicksburg? If so, and if the earth were to (magically, with no inertial complications) stop rotating, would that water start to run northwards?

Silas
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Old 20 March 2007, 03:02 AM
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Okay, my head is still spinning from reading your question, but I do remember hearing that the Mississippi did temporarily reverse it's course after the New Madrid earthquake of 1812.
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  #3  
Old 20 March 2007, 04:02 AM
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From Wikipedia:
Quote:
Other changes in the course of the river have occurred because of earthquakes along the New Madrid Fault Zone, which lies between the cities of Memphis and St. Louis. Three earthquakes in 1811 and 1812, estimated at approximately 8 on the Richter Scale, were said to have temporarily reversed the course of the Mississippi. These earthquakes also created Reelfoot Lake in Tennessee from the altered landscape near the river. The faulting is related to an aulacogen (geologic term for a failed rift) that formed at the same time as the Gulf of Mexico.
I don't see how the Coriolis effect could counteract the gravity, mass, and inertia involved in a flowing river. It doesn't determine the direction of a toilet's flush, so how could it do so to a river?

Last edited by PrometheusX303; 20 March 2007 at 04:03 AM. Reason: URL didn't work
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  #4  
Old 20 March 2007, 04:34 AM
Salamander Salamander is offline
 
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Hmmm... I guess it depends on how strongly you adhere to your Flat Earth principles Silas

If you temporarily forget the obvious truth that the world is flat and go with the silly "globe" model, I guess you could argue that any sufficiently long river runs "uphill" based upon the curvature of the Earth's surface. It'd be the same logic that suggests that if we begin walking on the surface of a globe, no matter which way we go, it is downhill.
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Old 20 March 2007, 05:02 AM
Troberg Troberg is offline
 
 
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The coriolis effect is very real and could have a real effect. I doubt it strong enough to actually pull a river uphill, but it can certainly propel it on level ground.
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  #6  
Old 20 March 2007, 05:26 AM
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Working our way south down the Mississippi:

St Lous, MO; elevation 465 ft

Memphis, TN; elevation 337 ft

Greenville, MS; elevation 128 ft

Vicksburg, MS; elevation 85 ft

Vidalla, LA; elevation 65 ft

Baton Rouge, LA; elevation 53 ft

New Orleans, LA; elevation -6 to 20ft

I think that's pretty much downhill all the way from St Louis the New Orleans.
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  #7  
Old 20 March 2007, 07:02 AM
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UEL UEL is offline
 
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Teacher Mississippi River and Survey Gone Mad

Quote:
Originally Posted by Silas Sparkhammer View Post
The story may be relying on the earth's equatorial bulge, and on "centrifugal force" (not Coriolis) in which case, hm.... Is, say, the river level at New Orleans farther from the center of the earth than the river level at Vicksburg? If so, and if the earth were to (magically, with no inertial complications) stop rotating, would that water start to run northwards?

Silas
I've got data for you.

I took the location of the bridge crossing at Vicksburg, including its height above sea level, and calculated its location from the centre of the earth. I then compared it with the data from the very last habitation on the Mississippi River before it empties into the Gulf of Mexico. This was done by converting the lat/long into Cartesian coordinates (gawd, its been long since I've done that) and then comparing the data with the centre of the WGS-84 ellipsoid.

By lucky coincidence, the two points were exactly 200 NM apart. Anyways, the mouth of the Mississippi is 988 metres further away from the centre of the earth** than the river going under the bridge at Vicksburg.

Calculations are available if anyone really wants to double check my maths.

I do not think that the Coriolis force has any effect on the flowing river, as for much of the Mississippi path, there are other rivers, eg the Red, flowing in the opposite direction.

** To be exact, it is 988 metres further away from the centre of the WGS-84 ellipsoid. The earth does not conform perfectly with this ellipsoid, although it is close.
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Old 20 March 2007, 10:07 PM
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Silas Sparkhammer Silas Sparkhammer is offline
 
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Whalephant

Quote:
Originally Posted by UEL View Post
. . . the mouth of the Mississippi is 988 metres further away from the centre of the earth** than the river going under the bridge at Vicksburg. . . .

** To be exact, it is 988 metres further away from the centre of the WGS-84 ellipsoid. The earth does not conform perfectly with this ellipsoid, although it is close.
Okay, I think this may be what the UL had in mind. The river runs downhill with respect to "Sea Level" but not with respect to "The center of the earth."

The ellipsoid itself is due to the rotation of the earth, isn't it? So, again, if we could miraculously stop that rotation (anyone here named Joshua?) the centrifugal force would be gone, and the water at New Orleands would "realize" that it was higher than the water at Vicksburg, and try to run northward...right?

Silas (omega r squared)
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  #9  
Old 21 March 2007, 01:31 AM
Howard
 
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I dunno about all that, Silas.

I thought it was the force of the water flow combined with the sea level and path of least resistance.
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  #10  
Old 21 March 2007, 02:17 AM
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If the earth stopped, and if the ellipsoid is no longer elongated due to rotational force, then all would be equal, and the sea level would still be the determining factor.
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  #11  
Old 21 March 2007, 02:19 AM
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Quote:
Originally Posted by Silas Sparkhammer View Post
Okay, I think this may be what the UL had in mind. The river runs downhill with respect to "Sea Level" but not with respect to "The center of the earth."

The ellipsoid itself is due to the rotation of the earth, isn't it? So, again, if we could miraculously stop that rotation (anyone here named Joshua?) the centrifugal force would be gone, and the water at New Orleands would "realize" that it was higher than the water at Vicksburg, and try to run northward...right?

Silas (omega r squared)
Given that this is all hypothetical, if the earth stopped spinning, the shape of the earth would likely rebound too. Probably not as fast as water flowing, but the river could very well be flowing normally again a day or two later. That is, once all the aftershocks from the life shattering earthquakes were finished.

I went further with my calcs last night and I found out that the poles are 21 plus kilometres closer to the centre of the earth than the equator. That's a big difference.
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  #12  
Old 21 March 2007, 02:41 AM
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Silas Sparkhammer Silas Sparkhammer is offline
 
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Whalephant

Hambubba and UEL: that's why I specified the "magical" non-rotation. Maintain the ellipsoid, but remove the centrifugal force. I'm almost certain that what I'm visualizing is correct; I just wanted to see if you agreed.

Many thanks to UEL and Beachlife for the actual numerical data!

(A polite "neener neener neener!" to Salamander, who, of course, understands that the sphericity, or ellipsoidy, of the earth is every bit as hypothetical as its magical cessation of rotation, all merely mathematical conjectures, ala Ringworlds, Dyson Spheres, Hollow Earths, or Bizzarro [cubical] Earths.)

Silas (believes nine impossible things before brunch)
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  #13  
Old 21 March 2007, 04:07 PM
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UEL UEL is offline
 
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Default Earth rotation stopped

Silas, I knew you were referring to a magical stopping of the earth's rotation, but I like to imagine to the third order any effect that might occur because of any geological change.

Thus, your challenge also stroked my hypothetical curiosity as well.
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  #14  
Old 21 March 2007, 07:18 PM
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CannonFodder CannonFodder is offline
 
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Quote:
Originally Posted by UEL View Post
I've got data for you.

I took the location of the bridge crossing at Vicksburg, including its height above sea level, and calculated its location from the centre of the earth. I then compared it with the data from the very last habitation on the Mississippi River before it empties into the Gulf of Mexico. This was done by converting the lat/long into Cartesian coordinates (gawd, its been long since I've done that) and then comparing the data with the centre of the WGS-84 ellipsoid.

By lucky coincidence, the two points were exactly 200 NM apart. Anyways, the mouth of the Mississippi is 988 metres further away from the centre of the earth** than the river going under the bridge at Vicksburg.

Calculations are available if anyone really wants to double check my maths.

I do not think that the Coriolis force has any effect on the flowing river, as for much of the Mississippi path, there are other rivers, eg the Red, flowing in the opposite direction.

** To be exact, it is 988 metres further away from the centre of the WGS-84 ellipsoid. The earth does not conform perfectly with this ellipsoid, although it is close.
Zounds! You are definitely an Artillery officer.
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  #15  
Old 22 March 2007, 01:43 AM
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UEL UEL is offline
 
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Military Artillery Officer?

Egads CF, that is my degree speaking.

I only do the artillery for a paycheque
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  #16  
Old 24 March 2007, 11:37 PM
Singing in the Drizzle Singing in the Drizzle is offline
 
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If something did cause a river to start flowing backward. It would form a lake untill it could again start flowing down to the sea.
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