Coriolis Effect

Within its rotating coordinate system, the object acted on by the Coriolis effect appears to deflect off of its path of motion. This deflection is not real. It only appears to happen because the coordinate system that establishes a frame of reference for the observer is also rotating. The Coriolis effect is, therefore, linked to the motion of the object, the motion of Earth (the rotating frame of reference), and the latitude on Earth at which the object is moving.

Several illustrations of the Coriolis effect are described below. First, imagine that a cannon on the equator is fired to the north. The cannon ball will land farther to the right than its target because the cannon ball moving on the equator moves faster to the east than its target, which started out farther to the north. If the cannon is fired from the North Pole at a target toward the equator, the cannon ball will again land to the right of its true path because the target area has moved farther to the east faster. In other words, in the Northern Hemisphere, the cannon ball will always land to the right of its target no matter where it is fired relative to the target. In the Southern Hemisphere, the effect is reversed and the cannon ball will always fall to the left of its target.

The second involves an experiment demonstrating the Coriolis effect. Imagine a phonograph record on a turntable. The center hole is the North Pole, and the rim of the record is the equator. As the record turns on the table, a chalk line drawn across the record from the hole to the rim toward the person drawing the line will curve to the right.

A third example uses a carousel or merry-go-round to illustrate the Coriolis effect. As the carousel goes around, a rider on the carousel stands at the center (the North Pole) and throws the ball to someone standing on the ground beyond the edge of the carousel. From the ground, the ball appears to travel in a straight line, but, to the rider, the ball seems to travel in a curve.