Talk:Coriolis force

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Rotation direction

the coriolis/centrifugal force rotates to the right in the northern hemisphere and to the left in the southern hemisphere. So, please change main picture in article to include both rotations

Intuitive application to Earth

Disputed section:

A particle traveling east would tend to follow straight on, lifting off in a plane perpendicular to the axis. The projection of that on the ground, to which the particle is bound by gravity and pressure, veers off towards the equator. Conversely, a particle moving west does not keep up with the ground speed and pursues its straight course bending down towards the axis, sliding off towards the pole.

How is this wrong? The particle moves west relative to the ground, so in absolute view it does not move fast enough to keep up with the ground moving east. Try to imagine it. A moment later the ground has rotated a certain angle, so the original horizontal direction now cuts into the ground going west. Anyway, it cannot be wrong, because it follows from the exact formula. Other people found it enlightening (see under 2). −Woodstone (talk) 16:15, 19 August 2010 (UTC)

Maybe it's not wrong. But it is not explained clearly enough to avoid giving the wrong idea. I don't understand exactly what it's trying to say, and I'm pretty good with geometrical reasoning. To me, an intuitive explanation is that since motions on the surface of the earth are constrained to a 2D surface, only the component of the earth's rotation about local vertical contributes to the Coriolis effect. Wherever you are you can think of the ground rotating beneath your feet, just as it does at the pole, but the rotation rate is given by the angular velocity vector of the earth projected onto the local vertical. That makes it clear that east-west motion is fundamentally no different from north-south motion.Rracecarr (talk) 13:27, 20 August 2010 (UTC)

Yes, that is fully correct, but it is just stating in words what is said by the formula in the next section. What people have been asking for is an explanation more from an inertial viewpoint, so without invoking the formulas. For North/South movement that is easy to do by showing the inertial gain/loss over groundspeed. For East/West movement it is more difficult, since it involves both the 3rd dimension (up/down) and the 2 dimensional limitations imposed. That is what the contended phrases try to do. At least one other editor liked the explanation. −Woodstone (talk) 14:59, 20 August 2010 (UTC)

I don't think there is anything wrong with stating in words what the math says. Some people find it easier to read words. If there is a way to avoid words like "angular velocity vector," I'm all for it, but as it stands I don't understand what the meaning of the explanation. The explanation for an eastward moving particle sounds like it just explains curvature toward the equator along the great circle route, which would occur without rotation and has nothing to do with Coriolis. For westward moving particles, I don't understand what is meant by "does not keep up with the ground speed". Rracecarr (talk) 17:17, 20 August 2010 (UTC)

Acceptable editing practice

rracecarr . Please do NOT blanket revert changes like this:

http://en.wikipedia.org/w/index.php?title=Coriolis_effect&action=historysubmit&diff=385164056&oldid=385155741

there are many edits here that were inserted individually to allow discussion of each issue and individual mods as needed. The only thing these have in common is that they don't suit you. That is not a valid reason to delete them , neither do many even relate to the comment you give as reason for the edit.

"undo many edits. the coriolis effect is fictitious in just the same way as the coriolis force"

As well as the fact that you don't seem to understand the subject if you can write that. The coriolis effect is REAL (at least the oceans and the atmosphere think to) , it is a real and direct result of inertia and the earths rotation. What is fictitious is the coriolos force. This fictitious force is needed in order to use newtonian mechanics in a rotational frame. You still don't seem to have grasped the basics here but persist in reverting any attempt to improve the article.

From now on please make single changes and justify each change with a credible comment rather than just undoing everything I do. —Preceding unsigned comment added by 95.176.116.89 (talk) 12:23, 7 October 2010 (UTC)

"Flow around low-pressure area" correction?

In the section, “Flow around a low-pressure area”, should “At high altitudes, outward-spreading air rotates in the opposite direction.” actually read “At high latitudes, outward-spreading air rotates in the opposite direction.”? And, does the writer mean “At high northern latitudes low-pressure areas turn clockwise.”? 76.212.128.2 (talk) 22:29, 18 December 2010 (UTC)

Bathtubs

Moved from the article. Materialscientist (talk) 05:43, 4 February 2011 (UTC)

The text below does not seem to state why water does indeed always drain one way out of the basin. It implies that only in rare cases would planetary rotation effects cause this, and yet it is observed to be true every time we flush or drain a sink (it always goes the same way). Even if this is due to 'residual' rotation in the 'container', would that not also be due to planetary rotation and the water in the container lagging being it? — Preceding unsigned comment added by 24.91.83.115 (talk • contribs)

I agree. The text covers the subject in detail and does not, in my opinion, contain any actual errors, however it does not give a clear answer on the subject to the casual reader. I suggest that some wording is added to the effect that the Coriolis effect is completely insignificant in all practical cases. Martin Hogbin (talk) 11:22, 6 February 2011 (UTC)

I would be inclined to double check that over a number of experiments. I have never found any preference as regards which direction water swirls out of a sink. Are you sure that you are not using the same sink each time and using water which has been given its angular momentum from the same tap? We all know that conservation of angular momentum occurs and that the vortex in the sink is a concentration of the existing angular momentum. But that existing angular momentum is generally speaking random. It's only in large scale atmospheric cyclones that the Earth's rotation is involved in determining the direction of the initial angular momentum. If I were you, I would do a few more experiments and report back if you are still getting anti-clockwise rotation everytime. The demonstrators at the equator, where the effect is least likely of all to occur, use squarish basins and they rotate as they stand up while picking the basin off the ground, so as to generate the preferred angular momentum. David Tombe (talk) 20:54, 6 February 2011 (UTC)