/* Last year, in first year I had problems with understanding the Coriolis Force. I asked the lecturer about it and he found a simpler way of explaining it. I thought I had understood. However, I've spent many hours this weekend trying to understand it and it keeps eluding me. That explanation from last year just fails to answer all my questions. Atm I feel very annoyed with the way lecturers and textbooks approach this topic. They derive the formula for the Coriolis force in a very general way using vectors, which gives absolutely 0 physical understanding. Then they try to bring the physics in by applying the Coriolis force to an object moving through a spinning disc. I feel this is an attempt to appeal to intuition that a lot of people don't have. Plus the example is usually presented in an unclear way where the student has to infer many details by themselves. */ My current understanding of the Coriolis force is this: every point on the surface of the Earth rotates with the same angular velocity ω but the radius (to the axis of rotation) varies with the latitude. As an object moves to a region of different radius its angular momentum must be conserved, i.e. ω1r1 = ω2r2, so its rotational velocity becomes different to the rotational velocity of the Earth's surface at that point. This change is perceived to be caused by the Coriolis force. This may seem all good and well, but it seems to me that this force relies a lot on friction to function properly, or else how would the object acquire the Earth's rotational velocity in the first place. It's used to explain wind patterns, and I see no reason why air should be rotating with ω. Can some one tell me this: if a rocket flew in from space and reached a small distance above the Earth's equator, from there it proceeded to fly in a straight line to the North Pole (neglect the Earth's rotation about the sun for the moment), which way would it be deflected? It seems to me it would be deflected in the opposite direction to that which the Coriolis force predicts, as the Earth would be rotating under its straight path. Even if something just landed on the Earth (no previous rotational velocity) in a region where the coefficient of friction = 0, shouldn't the Earth just rotate "under" it since the object's mass provided inertia but there is no force being applied to it? If so shouldn't the "opposite Coriolis force" be present again? And if the Coriolis force really is dependant on friction, why is it a general feature of rotating frames?