Wind energy is one of the first sources of energy known to man.
The sun's rays are stronger nearer the equator than in the polar region. This heats the air in equatorial region and warm lighter air rises while cooler polar air moves in to replace it. This movement of air results in wind. Rotation of the earth and the local atmospheric conditions also affect the speed of wind. Wind moving at a greater speed has more energy than our muscular energy. This kinetic energy of the wind can be utilized in a number of ways.
The sheet is called the sail. In a single sail, if the wind is not blowing in the desired direction, the sail becomes useless. This problem is overcome using two sails, one sail is used to divert the wind and the second one collects this diverted wind. Christopher Columbus sailed to America in a sail boat.
A glider depends on the wind energy for its flight. Special surfaces on the wings of the planes can be manipulated by the pilot to change the way air flows around the wings, thereby controlling the lifts and the altitude of the plane.
