The water cycle removes salt from water through a process called evaporation.
Here's a breakdown of how the water cycle achieves this natural desalination:
- Evaporation: The sun's energy heats the ocean (or any body of saltwater), causing water to evaporate and turn into water vapor. Crucially, salt and other minerals do not evaporate with the water. They are left behind.
- Condensation: The water vapor rises into the atmosphere, cools, and condenses to form clouds. Because the water that evaporated was pure, the clouds are made of freshwater.
- Precipitation: The water in the clouds eventually falls back to Earth as precipitation – rain, snow, sleet, or hail. This precipitation is freshwater, containing virtually no salt.
- Runoff and Collection: The freshwater flows into rivers, lakes, and eventually back to the ocean, restarting the cycle. While runoff can pick up some minerals on its journey, the vast majority of water that evaporates is significantly less salty than the ocean.
In essence, the water cycle acts as a massive, natural desalination system, continuously separating freshwater from saltwater through evaporation and condensation. This is why rainwater is fresh, even though it originates from the salty ocean.
