WaterCycle.
Waterstartsinitsliquidform,whichiswateraseveryoneknownalready.Whenwaterinlakes,oceansisheatedupitturnsintowatervapours.Watervapourscooldownandformcloudsinthesky.Cloudshastoomanyvapoursinitandcannotholdanymore,itrains.Thewatergoesbackintolakesandoceanswhenitrains.Andthewaterisreadyforanothertravel