What role does water vapor play in cloud formation?

Water vapor plays a critical role in cloud formation primarily because it can condense to form droplets. When air rises, it expands and cools due to lower atmospheric pressure. As the air cools, the water vapor within it reaches its dew point, leading to condensation. This process transforms the gaseous water vapor back into liquid water droplets, which cluster together to form clouds.

The significance of condensation in cloud formation cannot be overstated; it is through this transition that the visible mass of water in the form of clouds is created. Without sufficient water vapor to condense, clouds would not form at all. The amount of water vapor present in the air fundamentally determines the potential for cloud development, as well as the types of clouds that form. Thus, the correct response highlights the essential process that leads to the formation of clouds in the atmosphere.