Wind turbines convert the kinetic energy in the wind into mechanical power.
Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities 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. Since earliest recorded history, wind power has been used to move ships, grind grain and pump water. Within several centuries before Christ, simple windmills were used in China to pump water.