Which term describes the energy source for the water cycle?

• A. The wind.
• B. The sun.
• C. Geothermal energy.
• D. Moonlight.

Answer: (B)

Sunlight provides the energy that powers evaporation, the first step of the water cycle. When the sun heats oceans, rivers, and soil, water molecules gain enough energy to become vapor and rise into the air. Plants also contribute through transpiration, releasing water vapor from their leaves. This solar energy drives not just evaporation but the whole cycle of evaporation, condensation, precipitation, and collection. Wind is a consequence of solar heating and helps move moisture, but it isn’t the energy source for the cycle. Geothermal energy comes from inside Earth and is not the primary driver of the global water cycle, and moonlight is just reflected sunlight with far less energy.