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The Sun lifts water out of the sea. Where does it go, and how does it get back?
Water Cycle lab · Last updated: 16 October 2026
You follow water on its endless journey: lifted from the sea by the Sun's heat, carried as vapour, gathered into clouds, dropped as rain and returned through rivers and underground. The water cycle supplies every glass of drinking water, and in India it brings the monsoon that farms depend on.
What you'll discover
- The Sun's heat turns water from seas, lakes and plants into invisible water vapour.
- As the vapour rises and cools, it condenses into tiny droplets that make clouds.
- Rain and snow return water to the land, where it flows back through rivers and underground to the sea.
The science in plain words
Almost all of Earth's water, about 97 per cent, is salty water in the oceans. The water cycle moves it round the planet, powered by energy from the Sun. When sunlight warms the sea, some water evaporates, turning into invisible water vapour. Salt is left behind, so the vapour is fresh water. Plants also release water vapour from their leaves, a process called transpiration.
Warm, moist air rises. Higher up the air is cooler, so the vapour condenses onto tiny specks of dust, forming droplets so small they float. Billions of them together make a cloud. Inside the cloud, droplets bump together and grow. When they become too heavy to stay up, they fall as rain, or as snow or hail if it is cold enough. This is precipitation.
Rain that reaches the ground may run off into streams and rivers, soak into the soil and become groundwater, or be stored for a while as ice and snow on mountains. Sooner or later most of it flows back to the sea and the cycle begins again. The same water has been going round for billions of years. India's monsoon is part of this cycle on a grand scale: summer winds carry moist air from the oceans over the land, bringing most of the year's rain.
Where it fits
- India, NCERT: Class 6 science, Chapter 8: A Journey through States of Water
- United States: Grades 6 to 8
- Next Generation Science Standards: MS-ESS2-4
Common questions
What are the stages of the water cycle?
The main stages are evaporation, when the Sun's heat turns water into vapour; condensation, when vapour cools into the droplets that form clouds; precipitation, when water falls as rain, snow or hail; and collection, when water gathers in rivers, lakes, soil and the sea.
Why is rain not salty if it comes from the sea?
When seawater evaporates, only the water turns into vapour. The salt is left behind in the sea. So the vapour that rises, forms clouds and falls as rain is fresh water. This is the same idea used in solar stills to make drinking water from seawater.
What powers the water cycle?
The Sun powers the water cycle. Its heat evaporates water and drives the winds that carry moist air around the planet. Gravity then brings rain and snow back down and makes rivers flow downhill to the sea, completing the loop.
Related labs
- States of Matter: Solid, liquid, gas: the same molecules, just jiggling harder.
- Weather Patterns: Why does wind swirl round a storm instead of blowing straight in?
- Erosion: Pour water on a slope of sand: where does the sand go?
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Try it yourself
The Water Cycle lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.