coriolis
The Coriolis effect describes how Earths rotation steers winds and surface ocean currents. Unlike land, air and water move freely in the absence of obstacles . The Coriolis effect causes the path of a freely moving object to appear to curve. This is because Earth is rotating beneath the object. So even though the object's path is straight, it appears to curve. The curve appears to be to the right in the Northern Hemisphere. It appears to be to the left in the Southern Hemisphere.