1. The sun heats bodies of water (oceans, lakes, rivers, etc.) The water evaporates and becomes water vapor that moves into the air.
2. Water vapor rises high in the air. The air cools. The water vapor condenses into tiny water droplets to form clouds.
3. Billions of drops come together to form bigger drops of water. When the drops are too heavy, they fall to the Earth's surface as rain, snow or hail.
4. Some of the precipitation falls into rivers, lakes, and oceans. Some soaks into the ground. Rivers and ground water flow downhill into oceans and lakes.
5. The cycle repeats and continues.