A cloud forms when water vapor rises and the air higher up is cooler. The vapor changes into tiny liquid droplets. Which labeled process best matches this change, and what happens to energy?
State changes in the water cycle are physical, not chemical.
- Evaporation; energy is removed (cooling)
- Condensation; energy is removed (cooling) (correct answer)
- Condensation; energy is added (heating)
- Precipitation; energy is removed (cooling)
Explanation: This question focuses on understanding how water changes from gas to liquid state. Water changes state when it gains or loses energy, altering how its molecules are arranged and move. In the water cycle, condensation occurs when water vapor loses energy and forms liquid droplets, while evaporation happens when liquid water gains energy and becomes vapor. To analyze this change, identify that water vapor (gas) is becoming liquid droplets in cooler air, which means energy must be removed. Students often confuse condensation with precipitation, but condensation is the state change itself while precipitation is when droplets become heavy enough to fall. Water's ability to change state drives the water cycle, moving water from Earth's surface to the atmosphere and back. This process creates clouds, fog, and dew, redistributing water across different regions.