Wind Energy Wind is a form of solar energy . Winds are caused by the uneven heating of the atmosphere by the sun, the anomaly of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetative cover. This wind flow, or motion energy, when "harvested" by windturbines , can be used to generate electricity . Societies have taken advantage of wind power for thousands of years. The first known use was in 5000 BC when people used yacht to sail the Nile River. Persians had already been using windmills for 400 years by 900 AD in order to pump water and grind grain. Windmills may have even been developed in China before 1 AD, but the earliest written documentation comes from 1219. Cretans were using "literally hundreds of sail-rotor windmills to pump water for crops and livestock." Wind Energy Sources Today, people are realizing that wind power "is one of the most promis