Why is the direction of centrifugal force acting parallel to the equator rather than perpendicular to the centripetal force on 3D rotating spherical objects like the Earth?
I'm having trouble understanding this because in 2D planes, the centrifugal force acts perpendicular to the centripetal force by Newton's Law which makes intuitive sense. However, for rotating 3D objects this only applies at the horizontal 2D cross-section which passes through the centre of mass, whilst at different latitudes it no longer acts perpendicular to gravity but is parallel to the equator shown by the red arrows in the picture.
My physics is not very advanced, so I'd appreciate any intuitive and relatively simple explanation.