Rain isn't salty because salt doesn't evaporate with water.
The Process of Rain Formation
The water cycle involves several stages, including evaporation, condensation, and precipitation. When the sun heats bodies of water like oceans, lakes, and rivers, the water turns into water vapor and rises into the atmosphere.
Evaporation and Salt
The key here is that salt does not evaporate along with the water. As noted in the reference, "The salt, however, will not evaporate with the water and so, the water in the glass should taste clean." This is also true in nature. Salt and other minerals remain behind when water evaporates from the ocean, while pure water vapor rises.
Condensation and Precipitation
- Evaporation: Water evaporates from bodies of water and enters the atmosphere as vapor, leaving salt behind.
- Condensation: The water vapor cools and condenses into water droplets, forming clouds.
- Precipitation: These water droplets grow larger until they fall back to Earth as rain, snow, or hail.
Why Rain is Freshwater
Since only water molecules evaporate, the resulting rain is essentially distilled water – freshwater devoid of salt and other minerals. This explains why rain tastes fresh, not salty, even though much of the water comes from the salty ocean. The entire process is a natural purification system.
The Water Cycle Simplified
| Stage | Description |
|---|---|
| Evaporation | Water turns into vapor and rises; salt remains behind. |
| Condensation | Water vapor turns into droplets, forming clouds. |
| Precipitation | Water droplets get bigger and fall to Earth as rain, snow, or hail. This is fresh and not salty. |
Examples
- Imagine boiling salt water in a pot. The steam (water vapor) that is produced is not salty, even though the water in the pot is salty. The salt stays in the pot while the steam is made up of pure water.
- Another example is a glass of seawater left in the sun. As the water evaporates, you will notice salt crystals left behind. These crystals are evidence that the salt did not evaporate with the water.
