Like almost all other form of energy, wind energy comes from the Sun. About 1 to 3 percent of the energy from the Sun is converted into wind energy. About 50 to 100 times more energy is converted into wind energy than into biomass by all the plants on earth. Most of this wind energy is at high altitudes where continuous wind speeds of over 160 km/h (100 mph) are common. Eventually, the wind energy is converted through friction into diffuse heat all through the earth's surface and atmosphere.

Sunlight heats different parts of the earth surface differently. Land is heated more quickly during the day (and cools faster during the night) than the sea, and areas near the equator are heated more than areas near the poles. The heated surface heats the air above it, which rises to about 10 km (6 miles) altitude (the top of the troposphere) and then spreads out to cooler areas where it falls. This convection system is what drives the earth's winds. The change of seasons, the spin of the earth, the irregular albedo of land and water, and the friction of wind over mountainous areas are some of the many factors which complicate the flow of wind over the surface.