In the water cycle, which process involves water vapor becoming liquid?

• A. Condensation
• B. Evaporation
• C. Precipitation
• D. Runoff

Answer: (A)

Condensation is the process where water vapor changes into a liquid. In the water cycle, rising water vapor cools as it climbs higher in the atmosphere, slows down its movement, and begins to stick together, forming tiny droplets. This is how clouds form, and it also explains why we see dew on surfaces when the air cools at night. Condensation releases energy as the substance moves from a higher-energy gaseous state to a lower-energy liquid.

Evaporation would be liquid turning into vapor, which is the opposite process. Precipitation is water that falls from clouds as rain, snow, or hail, not the change from gas to liquid. Runoff is water flowing over the land toward bodies of water, rather than a phase change.