Coriolis effect
Hi
I'm studying for exams and understand the Coriolis effect. However, I don't understand why it would apply when travelling just east to west or vice versa (bit I'm pointing to in the pic deflecting right). Surely the ground underneath rotates at the same speed relative to the wind the whole time when it's just east to west (or vice versa). I understand that if travelling north as in '2' below, the wind would be moving faster than the ground underneath it.
Can anyone explain please?