What is the primary driver of the water cycle?

The primary driver of the water cycle is the sun. Solar energy plays a crucial role in the process of evaporation, where water from oceans, lakes, and rivers transforms into vapor. The heat from the sun warms the surface of the water, causing this transformation. Once in the atmosphere, water vapor can cool and condense to form clouds, which eventually leads to precipitation, such as rain or snow, returning water to the Earth’s surface.

While the other factors listed, such as wind, gravity, and the earth's rotation, contribute to various aspects of the water cycle, they do not drive the cycle itself. For instance, wind aids in the movement of water vapor and helps distribute moisture but does not initiate evaporation. Gravity is essential for the movement of water across the landscape, enabling the flow of rivers and the drainage of water, yet it is not the source of energy that drives the cycles of evaporation and condensation. The earth's rotation influences weather patterns and ocean currents, but it is the sun's energy that fundamentally powers the entire water cycle.