Hi kids, do you know, all the water in our world goes round and round like the tire of a bicycle? Evaporation is the process by which water from rivers, lakes and oceans change from liquid to a gas called water vapor. Condensation is the process by which a gas changes into liquid form. In this case, water vapors become water droplets again.
When the clouds become full of water, the small water droplets join to become large drops of water which fall down as rain. All the water that falls as rain on the land flows down towards the oceans. This includes streams, rivers, waterfalls and is called surface runoff.