# Why does air moving from Equator to Poles deflect to right in Northern Hemisphere due to Coriolis Force?

apologies if this is the wrong place to post this question in, but I am having a really hard time grasping Coriolis Effect.

My current understanding is that -

Let's say there's a point midway from Equator and North Pole. This point has a low pressure, and the areas near North Pole and Equator have high pressure.

Areas away from the equator move slower, compared to the areas close to equator. Therefore, a wind flowing up will deflect to the left to meet the low pressure region, similarly, a wind flowing from North Pole to the point will deflect right since the point is moving faster than the pole.

But, at the same time, I ended up with this counter argument, winds close to Equator will have a higher velocity component along the West to East direction, so when they flow up, they get deflected to right, and similarly, winds in North Pole having a low velocity component along West to East will deflect to left.

Now, I am very unsure what is the flaw in my logic.

Any help would be appreciated! Thank you!

• You are in the wrong frame of reference - from the outside, the rest frame, there is no Coriolis force. Your blue arrow goes straight, instead of curved. The C exists only in a co-rotating, non-inertial frame. There, it attains a minus w.r.t. direction you are thinking about. Commented Feb 28, 2023 at 23:02

Therefore, a wind flowing up will deflect to the left to meet the low pressure region, similarly, a wind flowing from North Pole to the point will deflect right since the point is moving faster than the pole.

I'm not sure, what you mean by "flowing up", but I'm assuming you mean "flowing poleward". At any rate, the Coriolis force is completely independent of the pressure field - it is a purely kinematic law. The pressure difference only drives the poleward movement, which is, in turn, deflected by the Coriolis Force.

To illustrate, imagine you are standing on the north pole and you throw a ball south (really hard). The ball will fly straight south whereas the earth beneath it is rotating eastward (to the left from the north pole perspective). This means, from the earths perspective, the ball is bending to the right.

Similarly, If you're standing on the equator and you throw a ball northward, it has a higher eastward velocity compared to the earth's surface more northward. This means, from the ball's perspective, the earth is rotating westward, or, to the left and from the earth's perspective, the ball is, again, deflected to the right.

I think you are just confusing your self by mixing terminology. stick to east and west not left and right, or even just use 2 axis, with or against spin, and towards or away from the equator (the fastest part).

Air moving towards the equator will bend away from the direction of spin. Air moving away from the equator will bend with the direction of spin.

Also don't forget you are looking at a circulation not movement in one direction.

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Here are two good video that may help, this is difficult to explain with static images.