# What are the physics behind the Coriolis effect? [closed]

What causes the Coriolis effect?

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## closed as not a real question by ja72, Waffle's Crazy Peanut, Chris White, Brandon Enright, Michael BrownMay 31 '13 at 9:05

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Wikipedia is your friend: en.wikipedia.org/wiki/Coriolis_effect – Hydro Guy May 29 '13 at 21:10
In what situation or context are you asking? Question needs more information. – ja72 May 29 '13 at 21:13
Well in anything moving on the earth, such as ocean currents. – Ovi May 29 '13 at 21:14
The whole point is that you are on a non-inertial system of coordinates, in the case, one that rotates with earth. If you write down the equations of it, you will perceive that there is a dependence with the angular velocity vector and with the position, in such way that you will probably get a minus sign when you pass through the equator, and so, you get things moving in opposite ways. – Hydro Guy May 29 '13 at 21:21
Use Google to find a classic film, "Frames of Reference" with Hume and Ivey... (Had both of them as profs, a loooong time ago) – DJohnM May 30 '13 at 0:12

@Ovi Your analogy implicitly assumes the Earth is a cylinder. As you have just shown, there is no Coriolis effect when your velocity is parallel to the rotation axis. This agrees with the formula for the Coriolis force, which is proportional to $\vec{\Omega}\times\vec{v}$. Instead think of the other extreme - moving across one of the poles. Your non-inertial, Earthbound coordinates are rotating out from underneath your feet. – Chris White May 30 '13 at 4:15
Ok let's say the globe turns clockwise and we start the line at the south pole. If I move at $any$ angle (except 0 or 180) then the line will curve to the surface. However, the coriolis effect requires that objects turn clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. However, in our situation the line would always turn clockwise since the globe is rotating clockwise. – Ovi May 30 '13 at 4:28