Turntable

As disks and balls roll in a straight line across the spinning turntable, they appear to take a curved path. This apparent curving of things that move on a rotating surface is called the Coriolis effect.

This rotating table moves faster near the outer edges than it does at the center. When you place a disk on the table, the disk begins rotating at the same speed as that part of the table. The disk retains this speed as it moves through the faster-rotating outer areas, making it curve against the direction of rotation.

Earth’s rotation has a similar curving effect on the movement of air in the atmosphere and water in the oceans. That’s why you often see storm systems—such as hurricanes and nor’easters—take curving paths on weather maps. It’s also why winds circulate around storm centers.