When the clouds become too big and heavy with water droplets, the water starts falling to earth as either rain, fog, mist, dew, snow or hail depending on how cold it got high up in the atmosphere.
These are all types of precipitation. As condensation occurs the water droplets grow in size until eventually they become too heavy to remain suspended in clouds and they fall to the ground.
Hail forms when droplets of water freeze around a small core of ice. Hail stones increase in size by adding extra layers of ice as they are tossed up and down by rising and falling air in thunderstorms.
Snow forms when water vapour in the air changes directly to ice. Snowflakes are usually 6-sided ice crystals. The air temperature must be less than 0°C for snow to form.