The sun is indirectly responsible for many other forms of energy too. The sun’s rays cause tropical air to warm up and rise while cooler air from polar regions flows in to replace it. This creates winds that can be used for sailing ships, grinding grain, or even for producing electricity from windmill-powered generators.

Some persons have concluded that they would rather have a different way of life. They enjoy pollution-free power from their own windmill-powered generator. This source of power was common on farms in the past. But recently both individuals and the United States government have been giving windmills a second look.