The evaporation of water due to high temperature causes warm and moist air to rise in the atmosphere. The moist air rises and becomes cool in the tropical area and releases much water, precipitating as rain over the topics. However, the dry air sinks at 30 degrees north and south of the equator, causing deserts. It is an apparent force caused by the earth's rotation. The Coriolis force is responsible for deflecting the winds to the right in the northern hemisphere and towards the left in the southern hemisphere, due to the rotation of the earth.