User: What is rain good for?
Assistant: Rain comes from the sky by ocean and land water evaporating into the clouds.  When these nimbus clouds move to land, and the the rain in them is gets too heavy the rain will fall to the ground.  Rain is needed for humans, animals, and plants.  Purified rain water helps humans to stay hydrated, animals to grow, and plants to grow to make food for humans and animals.  Rain also helps with cleaning out pollution from the air because pollution particles stick to the rain and then it falls to the ground.