What is the primary role of the sun in the water cycle?

The primary role of the sun in the water cycle is to cause evaporation. The sun provides the energy needed to convert liquid water from oceans, rivers, and lakes into water vapor. This process occurs when sunlight warms the surface of the water, increasing the kinetic energy of the water molecules. As these molecules gain energy, they break free from the surface of the water and enter the atmosphere as vapor.

Evaporation is a critical phase in the water cycle, as it is the process that initiates the movement of water from bodies of water into the atmosphere. Once in the atmosphere, this water vapor can condense to form clouds, eventually leading to precipitation. Understanding the sun's role in this process highlights its importance in sustaining the entire water cycle, making evaporation the foundational process that drives the cycle forward.