The energy source that drives the water cycle is solar energy. The Sun heats water bodies, causing evaporation, which transforms liquid water into vapor. This vapor rises into the atmosphere, where it accumulates as clouds. When the clouds cool, precipitation occurs, returning water to the Earth's surface in the form of rain or snow. Solar energy not only facilitates this evaporation process but also influences weather patterns and climate conditions, emphasizing its pivotal role in the hydrological cycle and maintaining ecosystems.