If I throw a ball straight up, it deflects slightly to the west due to Coriolis forces. If instead I watch a bubble float up in water, is the bubble deflected west, east, or neither?
I think the bubble also moves west, but am not sure. My reasoning is that the air in the bubble must feel a Coriolis force to the west because it is rising. Further, as the bubble rises, the water around it moves, and the net motion of the water is down. Water moving down experiences a Coriolis deflection to the east. Bubbles move the opposite direction of water, so if the water is moving east, then the bubble should move west.
I don't have any reasonable-sounding counter-arguments, but I'm not completely convinced by my argument, either.
Edit: One reason I'm a unsure about this problem is that a bubble does not get thrown outward by a centrifugal force. Imagine a plastic ball filled with water and spinning fast. A bubble is sitting in the water in the equatorial place, half way to the edge of the ball. There's centrifugal force out towards the wall, but the bubble does not move that way. The bubble moves up the pressure gradient. The water gets thrown to the wall, and thus there is higher pressure at the wall than at the center. The bubble moves towards the center. If a bubble moves counter to the centrifugal force, I should be careful before claiming it moves with the Coriolis force.