Then start with the Earth's surface near the North Pole. It's almost like a rotating disc.pbuk said:Ah, but if my starting point is the Earth's surface then this understanding:
is no help to me: I cannot fire a cannonball into the surface of the Earth, and an object on a rotating disc cannot move north (up).
Yes, I do actually regret framing the question specifically about the Earth since I would have the same exact confusion with respect to an object traveling tangentially on a rotating disc.A.T. said:I don't think the decomposition of the Coriolis force based on the Earth surface (like done in Earth science) is relevant to the OP's question. The question can be answered using the basic definition of the Coriolis force in a rotating reference frame, which is independent of any specific surface. East-West translates to tangential movement with or against the reference frame rotation.
You're welcome. The radial Coriolis force component is a common source of confusion, because the definitions of the inertial forces in a rotating frame are based on mathematical simplicity, rather than ease of intuitive conceptualization. Here my explanation from a previous thread:person123 said:Thank you very much to everyone for all the posts; I'm still not that clear when it comes to relating the derivations with a conceptual understanding but it sort of makes sense to me.
A.T. said:One intuitive way to think about the radial Coriolis force, is as a velocity dependent modification of the centrifugal force. In fact you could order the inertial force terms in a rotating frame by direction, and lump the radial Coriolis force with radial centrifugal force. But for mathematical and historical reasons we separate them as position dependent term (centrifugal) and a velocity dependent term (Coriolis).