Wind energy is converted sun energy. The sun radiates energy onto the earth at an hourly rate of 174,423,000,000,000 kW hours. The earth is heated unevenly by the sun - the atmosphere heats up much more quickly in the equator regions than in the rest of the globe and dry land heats up (and cools down) more quickly than the oceans do. This differential heating of the earth drives a global atmospheric convection system: warm air is lighter than cold air and rises to altitudes of approx. 10 km; it then moves north- and southwards, while cold air moves underneath the warmed-up lighter air.
Because of the earth’s rotation, the air streams do not move straight towards the north and south, but circulate in the northern and southern hemispheres, but spiral in opposite rotation directions (hot air clockwise, cold air counter clockwise on the northern hemisphere). Ground surfaces interfere with this air-flow, resulting in different air pressures. Wind is the movement of air between pressure systems as they try to balance out.
It is estimated that 1-2% of the sun’s energy on earth is converted naturally into wind energy. A research study conducted at Harvard University concluded that a global network of wind power stations could meet the power consumption of the entire world population.