The sun is the source of most of the Earth’s energy. The sun’s energy comes to us as heat and light, which, in turn, give rise to other forms of energy. For example, the sun’s uneven heating of the Earth’s atmosphere is one cause of wind. Heated air expands and rises and is replaced by cooler air in a process called circulation. Circulation produces wind.
Additionally, carbon-based fuels are probably a result of the sun’s light. Most scientists believe that a combination of bacterial action, heat, and pressure transformed the plant and animal remains into crude oil and natural gas. Coal was formed in a similar fashion when thick layers of dead plants piled up in swamps and rotted, turning into a substance called peat. When layers of sediment covered the peat, the resulting pressure transformed it into coal. Because peat, coal, tar, bitumen, petroleum, and natural gas are believed to come from long dead plants and animals, they are often called fossil fuels.