Debunked: Rivers flow uphill

Rory

Senior Member.
I think it's time to stop.
Because you're not quite getting it, even though it's been explained to you many times over, and all the required information is right there in the thread (which you don't seem to have read closely enough). (I do understand and sympathise that language is an issue.)

My suggestion is for one person to carry on trying to explain, or maybe for the conversation to move to private messages, as it looks like this could go on for some time.

@Trailblazer seems game - he'd be my nomination. ;)
 

Trailblazer

Moderator
Staff member
@Trailblazer seems game - he'd be my nomination
I think I've said all that can be said.

In summary:

1) We measure heights above sea level, not above the centre of the Earth.

2) Sea level is, by definition, the lowest point that the waters will settle to, i.e. the lowest potential energy.

3) Sea level is further from the centre of the Earth at the equator than it is at the poles, because potential energy is the sum of both gravitational pull inwards and centrifugal force outwards.

4) It doesn't matter how far you are from the centre of the Earth: all that matters is whether you are above local sea level. If you are, then the sea is downhill from you.

5) WGS84 takes this into account, because it measures heights relative to a flattened ellipsoid which is a very close approximation of sea level, not relative to a sphere (or to the centre of the Earth, which is of course the same thing).
 

Rory

Senior Member.
I refuse to feel guilty about calling it "centrifugal force". We're in a rotating reference frame, so we feel centrifugal force, even if purists say it "doesn't exist". They can go and float in space and observe centripetal forces. :p

An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the force exerted by its rotation. A rotating body tends to form an oblate spheroid rather than a sphere. The Earth has an equatorial bulge of 42.77 km; this bulge is created by the greater centrifugal force at the equator and is independent of tides.

An often-cited result of Earth's equatorial bulge is that the highest point on Earth, measured from the centre outwards, is the peak of Mount Chimborazo in Ecuador, rather than Mount Everest. But since the ocean also bulges, like the Earth and the atmosphere, Chimborazo is not as high above sea level as Everest is.

https://en.wikipedia.org/wiki/Equatorial_bulge
Content from External Source
 
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txt29

Senior Member.
For those who are still confused and have troubles realizing why rivers flow as they flow, I try explaining it in simple terms that any person without any education in physics might understand:

Try imagining the Earth is made only of water. It would still have the pretty same ellipsoidal shape as the true Earth has, with the exception that there would be no hills. The Earth surface would be equal to the sea level. Everywhere and constantly. Still, the water surface on the Equator would be miles further from the center of the Earth than the surface on the poles. Despite it, the water would not flow away from the equatorial bulge ("down the hill"). It would be in equilibrium all over the planet.

Now, if you took a bucket of water, raised it over the surface, and poured down a ramp, it would always flow down to the sea level, regardless of your position on the Earth, and regardless of the direction and the length of the ramp.

It is as simple as that. You do not need to have any deep knowledge about gravitational and centrifugal force, or about your distance from the center of the Earth.

In other words, as stated already several times here in the thread, here on Earth we do not measure the altitude by the distance from the Earth center. We measure it as the distance from the sea level (in given place). And rivers follow the same logic - they flow from places elevated above the sea level, down to the sea.
 
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toutdoubt

New Member
what's amsl? let's remember people, a debunk is only as good as the number of people who can understand it.

Does he mean 'arbitrary'? Thought that meant based on personal whim, I think he meant whatever words means coincidental but but not important..thx
 
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