9.1. Cycles in Nature

In nature, many processes follow a repeating, circular pattern or cycle. Because of the Earth’s rotation on its axis, night follows day and day follows night. Because of the Earth’s revolution around the Sun, seasons complete their yearly cycle. Energy from solar radiation and the Earth’s internal heat are the driving forces behind the birth of new rocks and the rock cycle. The sun heats up the water in the oceans and starts the water cycle. Then clouds are formed from the evaporated water, and then water vapour from the clouds falls back to the surface as precipitation.