1. Nucleation: This is the process by which small clusters of atoms or molecules come together to form a liquid or solid phase. In the case of droplets, nucleation occurs when water vapor molecules cluster together to form tiny liquid water droplets.

2. Condensation: This is the process by which a gas turns into a liquid. In the case of droplets, condensation occurs when water vapor molecules collide with a cool surface and lose energy, causing them to turn into liquid water droplets.