What primary source of energy drives the Earth's water cycle?

The primary source of energy that drives the Earth's water cycle is the sun's radiation. The sun provides the necessary energy for evaporation, the first step in the water cycle. When the sun heats up bodies of water like oceans, lakes, and rivers, water molecules gain energy and transition from a liquid state to vapor in the atmosphere. This process is crucial for the formation of clouds, which is another key component of the water cycle.

Once water vapor condenses into droplets, it eventually falls back to the earth as precipitation, replenishing freshwater sources. The sun's heat not only initiates and sustains this cycle but also influences weather patterns and climate, which can affect the distribution and availability of water around the globe. Without the sun’s energy, none of the processes that make up the water cycle, such as evaporation, condensation, and precipitation, would occur.