This was discussed in the General Questions forum recently, but I can’t find any thread about it under Comments on Cecil’s Columns.
In the 1996 column, Cecil says “The real difference, apart from the end of life as we know it, would be that, no matter what hemisphere you were in, the bathwater would go straight down the drain.”. Please tell me this is a joke. We all know that bathtubs are much too small to be affected by the Coriolis Effect and the idea that you can tell what hemisphere you’re in by which way the water drains is an urban legend.
Also, I’m surprised the column contains no mention of the fact that the side of Earth facing the sun would get really really hot and the side facing away would get really really cold. I’d say that’s a bigger problem than bathtub drains.
Well said … the experiment has been conducted by which bath water is left alone for days, thus mostly eliminating all the pertinent friction forces (like eddies and currents). With nothing BUT the Coriolis effect, the water drains counter-clockwise in the Northern Hemisphere and clockwise in the Southern, and straight down at the equator.
In our non-rotating Earth, the water would drain straight down everywhere.
Let’s extend this a bit … I would say cyclones would spin both ways in both hemispheres … depending on the large scale circulation patterns. Perhaps someone skilled at tensor calculus can ferret out the solution using the stress tensor.
Terrain would provide the frictional forces to initiate the cyclones. Air would flow from the point where the sun remains overhead to its antipole. Any mountain ridge in the way provides the uplift and if it’s skew to the flow in anyway, you’ll have curl … cyclone would be initiated.
Actually, the column doesn’t really address what would happen if the earth stopped spinning, just what things would be like afterward.
The rotational speed of the earth is well under the earth’s escape velocity, so nobody would “fall off” the earth. However, everything not fixed to the earth would continue to move when the earth stopped, initially at the earth’s rotational speed, which is about 1670 km/hr at the equator. This would kill almost everyone on earth and would create a worldwide storm far more powerful than anything experienced since, I would guess, the K-T extinction event. Maybe more powerful than that, since that was initially a localized event at Chicxulub.
I have a feeling that whatever caused the Earth to no longer spin would be far more deathly than whatever effects the Earth suddenly stopped spinning would cause. I’m assuming that Cecil is talking about what would happen if the Earth slowly spun down in such a way not to cause terrible damage to the contents of the Earth itself.
Of course, there’s no absolutes in space. (This is why my sons always giggled when the captain of the Starship Enterprise orders it to comes to a full stop. Full stop in relationship to what? A nearby planet. A local star system? The spinning of the galaxy? Or the motion of the local galactic cluster?) The big question is whether the Earth is now tidally locked to the sun, so only one side of the planet is always facing the sun, or to the motion of its orbit, so that the Earth makes one rotation per year.
Either way, the weather patterns are bound to change as the side of the Earth to the sun heats up while the other side cools way down. I suspect there will be some pretty strong winds and storms due to these effects.
If the Earth stops spinning- forget it, we are all dead. Our atmosphere would be gone, the ozone layer would drift off into space and we would all be burnt alive by solar radiation before or after we drifted into space and died, because there would be no gravity holding us on the surface.
Ah, but that’s what would happen if the earth stopped rotating suddenly. How long it takes to stop is critical to an assessment of what effect that would have. If it takes a couple of centuries, I probably wouldn’t notice.
Did your post mean that such an experiment has demonstrated hemisphere-dependent drain swirl? If so, can you cite a reference? I do not believe that any such experiment has been able to show that. As a previous poster said, drain swirl direction being location dependent on Earth is an urban legend. The forces are just WAY too small to overcome other effects.
Citation sort of, the link is actually a review of Ascher Shapiro’s experiment that demonstrated that the Coriolis effect can be observed in a bathtub. A couple of rubs; in the absence of any and all other forces, then the Coriolis effect is enough (note in the citation they even had to cover the basin to remove air currents from effecting the water).
The second rub is that we’re not trying to explain why the vortex spins, only which direction. That’s determined at the instant the it forms. If you remember your calculus, then the magnitude of the vector over the time interval dt is indeed zero, but it retains it’s direction. It doesn’t matter how small a force is, when applied long enough, we can move the Earth.
Not an urban legend, both demonstrated and mathematically proven.