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My wife asked me what the Coriolis Effect was, so I did some research. I think I get it now but I'm surprised at the number of "explanations" people have uploaded that actually seem wrong. This one is an example.

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

This is wrong, right?

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  • $\begingroup$ Well - planes flying to a destination are not really like projectiles, so they would be dragged around by the air. It is definitely somewhat off in that regard, but it helps give a basic feeling for the Coriolis effect - things veer right on the Northern Hemisphere, and left on the Southern hemisphere, because the earth turns underneath them. In a rotating frame of reference, that veering is experienced as an apparent force. What specific bit of this "explanation" do you think is wrong? $\endgroup$
    – Floris
    Sep 5, 2014 at 3:53
  • $\begingroup$ I think the whole idea that the Coriolis effect is the earth rotating underneath objects is wrong. Consider the return flight from Miami to Alaska. It's in the northern hemisphere so the deflection should be to the right, but the "earth rotating underneath" theory would predict deflection to the left. $\endgroup$
    – retrosnob
    Sep 5, 2014 at 4:27
  • $\begingroup$ @retrosnob: The Coriolis effect IS DEFINED as the deflection caused by the pseudo-force that seems to act on masses in rotating coordinate systems. Since the Earth rotates, it generates a Coriolis effect by definition. The effect is, of course, measurable, even though one has to work a little, experimentally, to measure it correctly. $\endgroup$
    – CuriousOne
    Sep 5, 2014 at 4:45
  • $\begingroup$ Thanks CuriousOne, I get that, but I'm interested in the whole deflection to the right in the northern hemisphere thing. It seems that the Coriolis effect in meteorology can't solely be to do with a rotating reference frame, because that alone doesn't explain why cloud moving north is deflected right in the northern hemisphere. It seems to me that it has something to do with the speeds at which the ground moves at different latitudes. Is it that the Coriolis Effect in physics is subtly different from the Coriolis Effect in meteorology? $\endgroup$
    – retrosnob
    Sep 5, 2014 at 5:07
  • $\begingroup$ The latitude does come into it - since the apparent force is the vector product of the rotation of the earth and the velocity: so at lower latitudes (near the equator) the force appears smaller (the velocity towards the axis of rotation is smaller). A very nice explanation can be found in this earlier answer $\endgroup$
    – Floris
    Sep 5, 2014 at 5:29

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I would say that some parts are unclear, but no, it's not "wrong".

Consider the return flight from Miami to Alaska. It's in the northern hemisphere so the deflection should be to the right, but the "earth rotating underneath" theory would predict deflection to the left.

The animations are not showing that the cause is "the earth rotating underneath". If that were true, the line of travel would be fixed and not move along with the rotating earth. Instead it is (trying) to show that the different tangential speeds of the initial and final points cause problems for a travelling object that retains that speed.

A return flight would curve to the right as it went north, if it retained the extra tangential speed that it left with.

I would agree that final sentence: "In reality, pilots take the Coriolis effect into account so they do not miss their targets." is incorrect. Pilots take wind speed relative to the ground into account. There is no explicit correction for Coriolis in flight navigation.

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