Sun is the primary source of energy that causes changes in the weather because sun is a huge sphere of hot gases at a very high temperature. The distance of the sun from us is very large. Even then, the energy sent out by the sun is so huge that it is the source of all heat and light on the earth. Energy absorbed and reflected by the earth’s surface, oceans and the atmosphere play important roles in determining the weather at any place. Weather varies from place to place. It is different in a desert, near coastal areas or near a mountain.