Study guide: Water Cycle Water continuously circulates between Earth’s surfaces, the air, and under ground. This is called the water cycle. 3 2 1 1. The sun heats the water on Earth. The water evaporates (changes to a gas) into the air. 2. The water vapor condenses on particles and forms clouds. 3. The air changes from a gas to a liquid (rain) or to a solid (snow, sleet, or hail). precipitation The main energy source on Earth is the sun. The sun’s energy is called solar power. The sun gives us heat and light. The sun drives the water cycle. Without the sun the water cycle would stop. Most of the water on earth is ocean water. Fresh water for a community includes rivers, reservoirs, and wells. Although water is a renewable resource, pollution reduces the amount of usable water. Water pollution is usually made by trash, sewage, and chemicals being dumped in the water. The most dangerous water pollution is oil runoff from highways. We can conserve or save water by: Turning of the water when brushing your teeth. Turning it off between soaping and rinsing your hands. Running the dishwasher or washing machine only when it is full. Taking showers instead of baths. Limiting your shower time to 10 minutes or less. Fixing leaking faucets.