Explore the Cycle
Tap a numbered stop on the diagram — or press Play — to see how a drop of water travels through the whole cycle.
1. Evaporation
The sun heats up water in oceans, lakes, and rivers. The water warms up so much that it turns into an invisible gas called water vapor and rises into the sky.
The Five Stages
Here's the whole cycle in one place — water moves through these stages over and over, forever.
1. Evaporation
The sun heats liquid water and turns it into water vapor, which rises into the air.
2. Transpiration
Plants release water vapor from their leaves into the air — a plant's own kind of evaporation.
3. Condensation
High in the sky, cool air turns water vapor back into tiny liquid droplets, forming clouds.
4. Precipitation
When cloud droplets grow too heavy, they fall back to Earth as rain, snow, sleet, or hail.
5. Collection
Water gathers in oceans, lakes, and rivers, or soaks into the ground — ready to evaporate again.
Did You Know?
A few surprising facts about the water on our planet.
A raindrop might spend only about 9 days floating in the atmosphere as vapor — but water trapped deep in the ocean can stay there for thousands of years before it ever evaporates.
About 97% of Earth's water is salty ocean water. Less than 3% is fresh water — and most of that is locked away as ice.
More fresh water is stored underground as groundwater than exists in all the world's rivers and lakes put together.
Salt Water vs. Fresh Water
Not all the water in the water cycle is the same. Here's why the difference matters.
Salt Water
Found in oceans and seas. It's far too salty for people, most land animals, and most crops to drink — but it's home to an enormous amount of ocean life that has adapted to live in it.
Fresh Water
Found in glaciers, groundwater, lakes, and rivers. This is the water that people, land animals, and most plants depend on every day to survive.
🤔 Why Is the Ocean Salty?
As rain falls and flows downhill toward rivers, it picks up tiny amounts of minerals and salts from the rocks and soil it passes over. Rivers carry those dissolved salts all the way to the ocean.
When water evaporates from the ocean during the water cycle, only pure water rises into the sky — the salt gets left behind. Over thousands of years, more and more salt has washed in while only fresh water evaporates back out, so the oceans have grown saltier and saltier. (Some minerals also seep in from volcanic activity deep on the ocean floor!)
All of Earth's Water
Zooming Into That 3%: Earth's Fresh Water
Put it all together and less than 1% of all the water on Earth is fresh, liquid, and easy for people to reach — which is part of why fresh water is one of our planet's most precious resources.
💚 Why Fresh Water Access Matters
People, land animals, and most crops all need fresh water to survive — for drinking, cooking, growing food, staying clean, and keeping ecosystems healthy. Because so little of Earth's water is fresh and easy to reach, clean water isn't always easy to get everywhere in the world, which is why so many people and organizations work hard to protect and share it.
- Turn off the tap while brushing your teeth
- Take shorter showers when you can
- Tell a grown-up about leaky faucets
- Avoid letting hoses or sprinklers run longer than needed
Test Your Knowledge
Answer these 4 questions. Get 3 or more correct to master this lesson!