What causes the formation of clouds in the sky?
Description:
The correct answer is: Condensation of water vapor.
Explanation:
Clouds form when water vapor in the air cools and condenses into tiny liquid water droplets or ice crystals. This process typically happens when warm, moist air rises, expands, and cools as it moves to higher altitudes where the temperature is lower. The condensation occurs around tiny particles in the air, such as dust or pollen, known as condensation nuclei, but the primary cause of cloud formation is the condensation of water vapor.
The other options:
Accumulation of dust particles: Dust particles serve as condensation nuclei but are not the main cause of cloud formation.
Reaction of gases in the air: This is unrelated to cloud formation.