Let us consider a drop of water in a river. The droplet flows to a larger body of water such as a lake. From here, or even from the river, the droplet changes from the liquid to the vapor phase via the process of evaporation and goes into the atmosphere. In the atmosphere, the droplet is condensed back into the liquid phase in the form of cloud. When a sufficient amount of water has been created in the clouds, it precipitates back on to the ground and flows into rivers and streams again.
