exchemist
Veteran Member
I think the plughole thing is a bit of a myth. But indeed, you can ask @Flat Earth Kyle............., er no you can't, he seems to have been banned. Funny, that.
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ERATOSTHENES DID NOT PROVE THE EARTH IS A GLOBE!
- Thread starter Flat Earth Kyle
- Start date
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- Tags
- #flat earth
Subduction Zone
Veteran Member
It was done at MIT in the 60's or 50's with a large pool, of water that was allowed to stabilize for over a day. The also made sure to use a valve located some distance below the pool and other methods to eliminate turbulence. In a sink or a bathtub there is far too much turbulence in it already. The video that I posted showed a modern version of the MIT test. Done in both the Northern and Southern Hemispheres. They did not get a clear whirlpool, but various floating markers and dies showed that it was rotating as it drained.I think the plughole thing is a bit of a myth. But indeed, you can ask @Flat Earth Kyle............., er no you can't, he seems to have been banned. Funny, that.
Heyo
Veteran Member
The most ridiculous "spotlight" is during the winter when the Sun lights the complete circle of the Antarctic while it's dark at the North Pole. That requires some truly magical refraction.
exchemist
Veteran Member
I'd be interested in a reference to that, if you have one.
Subduction Zone
Veteran Member
I will have to see if I can dig it up again. I remember reading it but it has been years upon years.
Subduction Zone
Veteran Member
Okay I found it! Here is the paper, not peer reviewed from MIT:
I just started a general search that had the terms MIT, Coriolis, and pool in it. That article did not appear immediately instead I found this article that covered the video that I linked, they also point out that the team did not do their experiments just once. They did them three times each and had the same results each time:
The Coriolis and the Commode
www.americanscientist.org
" In fact, I have been told that graduate students at MIT still do this experiment today in one of their classes. The major difference between the past examples and the current YouTube version is that one was done in a lab with a fine control over outside forces and the other uses a kiddie pool set up on a plywood platform in a garage or sheltered patio. "
I was surprise that I remembered as many details that I did, such as it being covered. The time to allow turbulence from filling to die out and the sort of drain that they used to avoid affecting the pool improperly.
exchemist
Veteran Member
Hmm, but what I take from this is that the Coriolis effect will only determine the direction of swirl, in a 1.5m diameter pool, if the water inside is moving at <1.2ft/hr. i.e. extremely still. In practical terms, that means while the effect exists, it is far too weak to determine the direction of swirl in any real domestic situation. But the Rossby number is something I didn’t know about. I’ll have to look that up.Okay I found it! Here is the paper, not peer reviewed from MIT:
I just started a general search that had the terms MIT, Coriolis, and pool in it. That article did not appear immediately instead I found this article that covered the video that I linked, they also point out that the team did not do their experiments just once. They did them three times each and had the same results each time:
The Coriolis and the Commode
" In fact, I have been told that graduate students at MIT still do this experiment today in one of their classes. The major difference between the past examples and the current YouTube version is that one was done in a lab with a fine control over outside forces and the other uses a kiddie pool set up on a plywood platform in a garage or sheltered patio. "
I was surprise that I remembered as many details that I did, such as it being covered. The time to allow turbulence from filling to die out and the sort of drain that they used to avoid affecting the pool improperly.
P.S. I remember my grandfather trying to con me into thinking the Coriolis effect was why the carpet in his dining room had a tendency to rotate, over time.
wellwisher
Well-Known Member
I noticed an observation about the spherical earth, that is not easy to explain, with a spherical earth.
The earth is not a perfect sphere. It bulges at the equator. If we turned the earth on its side, using a globe, the equator is higher in terms of sea level; relative to the earth's core, than are the poles, since the diameter of the earth is greater at the equator. So why doesn't the water flow downhill from the bulging equator to the poles?
We do have the Gulf Stream, that flows north from the equator toward the poles. But that is attributed to the thermal gradient between the equator and poles, and not water finding its own level. The building of glaciers at the poles would raise the polar elevation and could serve as a global water balancing affect.
The earth is rotating; west to east, but the north and south movement needed is perpendicular, so this is not exactly connected to the spin. It will spiral the flow; west-east within the south-north vector. I hope climate change can explain this or else there may be missing variables. I am be factitious since there are extra variables.
The earth is not a perfect sphere. It bulges at the equator. If we turned the earth on its side, using a globe, the equator is higher in terms of sea level; relative to the earth's core, than are the poles, since the diameter of the earth is greater at the equator. So why doesn't the water flow downhill from the bulging equator to the poles?
We do have the Gulf Stream, that flows north from the equator toward the poles. But that is attributed to the thermal gradient between the equator and poles, and not water finding its own level. The building of glaciers at the poles would raise the polar elevation and could serve as a global water balancing affect.
The earth is rotating; west to east, but the north and south movement needed is perpendicular, so this is not exactly connected to the spin. It will spiral the flow; west-east within the south-north vector. I hope climate change can explain this or else there may be missing variables. I am be factitious since there are extra variables.
Well, you've proved substantially less than Eratosthenes did -- and you have a couple of millenia of human learning to refer to.
Subduction Zone
Veteran Member
Perhaps you are conflating the whirlpool one gets in a tub with rotation. You can see just a partial rotation by the time water gets within ten centimeters or so of the drain. With a regular whirlpool there are many full rotations before water goes down the drain. The motion is observable by using dyes and floating objects. Not from water rapidly circling the drain.
exchemist
Veteran Member
Erm... I don't follow. The article shows that the Coriolis effect only determines the direction of the incipient whirlpool if the Rossby number <1:
"In general, if the Rossby number is greater than 1, then the Earth’s rotational effect is negligible, meaning that the fluid can spin whatever way it wants to. If it is less than 1, Coriolis wins out."
Not sure why you are drawing a distinction between a whirlpool and rotation. This is about the direction of rotation of whirlpools, isn't it?
Subduction Zone
Veteran Member
A whirlpool is much more dramatic than a mere rotation. If an object rotates very slowly it will not generate enough centrifugal force to be visible to the naked eye. In other words, it rotates, but not very much. It is detectable using dies and objects floating on the surface in a room protected from air currents. In the video that I linked they each had done the experiment three times and had the same results. In MIT they do it regularly. But I have not seen that the rotation was ever strong enough to form a visible whirlpool.
exchemist
Veteran Member
OK I'm talking about the article about Coriolis and the Commode, which is about the myth about whirlpools rotating in opposite directions in different hemispheres. As I read it, the article says for the Coriolis effect to make a difference to the direction that the whirlpool starts to rotate, there must be no random motion within the water >1.2ft/hr, so it must be exceptionally still. If there are random currents then these will dominate over the Coriolis effect.
Alien826
No religious beliefs
I think the plughole thing is a bit of a myth. But indeed, you can ask @Flat Earth Kyle............., er no you can't, he seems to have been banned. Funny, that.
He's banned? If so I guess he deserved it, but I personally like these people with totally crazy ideas, as they provide much needed humor.
exchemist
Veteran Member
Well you can't look him up any more. He's gone. He was a twat, though.
As if we needed more comedians.
Heyo
Veteran Member
The water is "higher" at the equator for the same reason there is a bulge at the equator. The centrifugal (pseudo) force pushes it "up". When you rotate a bucket the water is also "higher" at the sides than in the centre.
Subduction Zone
Veteran Member
That is true without a doubt. The experiment showed that if one went to extreme measures that one could detect rotation, but that was about it, in a two meter wide pool. Commodes whirl the way they do due to the jets that release the water. A sink or bathtub will drain depending upon initial (or in a bathtub often continuing) turbulence. I remember watching whirlpools and eddies as a youngster in the bath and how they sometimes switched directions. That one is pure myth. I also saw about ten years ago some rather talented scam artists (just minor ones) that would fool tourists in Ecuador. At a park that was on the equator they could show how water went one direction north of the equator and reversed it in the same portable basin when they crossed to the south. Only one problem. They had their direction of rotation backwards.
Alien826
No religious beliefs
Looks like I started something. I was right about the weather patterns (cyclones) though.
exchemist
Veteran Member
Oh sure. The Coriolis effect affects many phenomena. I've even seen it suggested that it may cause uneven wear on railway tracks. (But not my grandfather's carpet! He was just a structural engineer, pulling his grandson's leg.)