NASA | Earth Science Week | What are the Primary Forces ...

The sun is the primary force in Earth's climate system. Sunlight warms our world. Sunlight drives atmospheric and oceanic circulation patterns. Sunlight powers the process of photosynthesis that plants need to grow. Sunlight causes convection which carries warmth and water vapor up into the sky where clouds form and bring rain. In short, the sun drives almost every aspect of our world's climate system and makes possible life as we know it.