The water cycle (also called the hydrologic cycle) is the never-ending journey of water as it moves between the ocean, the sky, and the land. The same water is used over and over: it rises into the air, forms clouds, falls back to Earth, and flows back to where it started. On this page you will find every stage explained in order — evaporation, condensation, precipitation, and collection — a clear diagram, worked examples, and an interactive trainer where you can name each stage yourself.
What is the water cycle?
The water cycle is the continuous movement of water on, above, and below the surface of the Earth. Water is never created or destroyed — the same water simply changes state and location again and again. It can be a liquid (ocean, rivers, rain), a gas (invisible water vapor in the air), or a solid (snow and ice).
The energy that powers the whole cycle comes from the Sun. Sunlight heats water in oceans and lakes, turning it into vapor that rises into the sky. Gravity then pulls the water back down as rain or snow, and it flows across the land back toward the sea. Because it loops around with no beginning and no end, we call it a cycle.
Understanding the water cycle explains where rain comes from, why it is cloudy some days, and how a drop of water in the ocean can end up in a mountain river weeks later.
Stages of the water cycle and how it works
The water cycle works in a repeating loop of four main stages, powered by the Sun and gravity: evaporation → condensation → precipitation → collection, and then it starts over. A fifth process, transpiration, adds water vapor from plants. Follow the loop in the diagram below — the last stage always feeds back into the first.
Each stage explained: evaporation, condensation, precipitation, collection
Evaporation is when the Sun's heat changes liquid water into a gas called water vapor. It happens most over warm oceans and lakes. The vapor is invisible and rises because warm air is lighter than cool air.
Transpiration is like evaporation but from plants. Trees and grasses draw water up from the soil and release it as vapor through tiny pores in their leaves. Together, evaporation and transpiration are sometimes called evapotranspiration.
Condensation is the opposite of evaporation. High in the atmosphere the air is cold, so the vapor cools and turns back into tiny liquid droplets. Billions of these droplets clustered together are what we see as clouds. (The same thing happens when droplets form on a cold glass of water.)
Precipitation happens when cloud droplets combine until they are too heavy to float. Gravity then pulls them to the ground as rain, snow, sleet, or hail, depending on the temperature.
Collection (also called runoff) is the final stage. Fallen water flows downhill into streams, rivers, lakes, and the ocean, or it soaks into the soil to become groundwater. Once it is collected, the Sun can evaporate it again — and the whole cycle repeats. The table below sums up each stage at a glance.
| Stage | What happens | Where |
|---|---|---|
| Evaporation | Liquid water turns into water vapor | Oceans, lakes, rivers |
| Transpiration | Plants release water vapor from their leaves | Forests, fields, grass |
| Condensation | Vapor cools into droplets and forms clouds | High in the sky |
| Precipitation | Water falls as rain, snow, sleet, or hail | From clouds to the ground |
| Collection | Water gathers or soaks into the ground (runoff) | Oceans, rivers, soil |
Why the water cycle matters
The water cycle is one of the most important systems on Earth. It:
- Provides fresh water. Evaporation leaves salt behind in the ocean, so the rain that falls is fresh water we can drink and use for farming.
- Shapes the weather. Clouds, rain, snow, and storms are all steps of the cycle in action.
- Moves energy and heat around the planet, helping to keep temperatures balanced.
- Connects every part of the world. A drop that evaporates from the Pacific Ocean might fall as snow on a mountain and flow through a river months later.
Because the same water is recycled forever, keeping it clean matters: pollution added anywhere in the cycle can travel far and come back around.
Worked example: follow one drop of water
Walkthrough: a raindrop's full journey
Let's follow a single drop of water all the way around the cycle so you can see how the stages connect.
Start — in the ocean. Our drop is floating in the warm surface water of the Pacific Ocean.
Step 1 — Evaporation. The Sun heats the surface. The drop gains energy, turns into invisible water vapor, and rises into the air. (Notice the salt stays behind in the ocean — that is why rain is fresh water.)
Step 2 — Condensation. High up, the air is cold. The vapor cools and turns back into a tiny liquid droplet. It joins millions of other droplets to form a cloud.
Step 3 — Precipitation. The wind blows the cloud over land. The droplets keep joining until they are heavy, and our drop falls as rain.
Step 4 — Collection. The raindrop lands on a hillside and runs downhill (runoff) into a stream, then a river, and finally back to the ocean — or it soaks into the soil as groundwater.
Back to the start. Once it reaches warm water again, the Sun can evaporate it, and the whole journey repeats. The drop was never used up — it just kept changing state and place.
Common mistakes about the water cycle
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Mixing up condensation and precipitation.
Condensation is when vapor turns into droplets and forms clouds — the water stays up in the sky. Precipitation is when that water actually falls to the ground as rain, snow, or hail. Clouds form first (condensation); rain comes later (precipitation).
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Thinking water gets 'used up' or that new water is created.
Water is never created or destroyed in the cycle. The same water is recycled endlessly — it only changes state (liquid, gas, solid) and moves to a new place. The drop you drink today may have been rain on the other side of the planet years ago.
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Confusing evaporation and transpiration.
Both add water vapor to the air, but the source is different. Evaporation comes from open water like oceans and lakes. Transpiration comes from plants releasing vapor through their leaves. Scientists sometimes combine them into one word: evapotranspiration.
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Believing clouds are made of water vapor.
Water vapor is an invisible gas — you cannot see it. A cloud is made of tiny liquid water droplets (or ice crystals) that formed by condensation. That is exactly why you can see a cloud but not the vapor around you.
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Thinking the cycle has a fixed start or finish.
The water cycle is a loop with no true beginning or end. We usually start explaining it at evaporation because the Sun powers it, but collection flows straight back into evaporation, so it just keeps going.
Water cycle: questions and answers
What are the four main stages of the water cycle?
The four main stages are evaporation, condensation, precipitation, and collection (runoff). Evaporation turns liquid water into vapor, condensation forms clouds, precipitation brings rain or snow, and collection gathers the water so the cycle can start again. Transpiration from plants is often added as a fifth process.
How does the water cycle work in simple terms?
The Sun heats water and it evaporates into the air as vapor. High in the sky the vapor cools and condenses into clouds. When the clouds get heavy, water falls as precipitation (rain or snow). That water collects in rivers, lakes, and oceans, then evaporates again — a never-ending loop powered by the Sun and gravity.
What is the difference between evaporation and condensation?
They are opposites. Evaporation changes liquid water into a gas (water vapor) using heat from the Sun. Condensation changes water vapor back into a liquid when the air cools. Evaporation sends water up into the sky; condensation forms the clouds up there.
What powers the water cycle?
The Sun provides the energy. Its heat drives evaporation, lifting water into the atmosphere. Gravity then does the rest of the work, pulling precipitation down and moving collected water downhill toward the sea.
What is precipitation in the water cycle?
Precipitation is any form of water that falls from clouds to the ground. It can be rain, snow, sleet, or hail, depending on the temperature. It happens when cloud droplets combine until they are too heavy to stay in the air.
What is transpiration and how is it different from evaporation?
Transpiration is when plants release water vapor into the air through tiny pores in their leaves. It is similar to evaporation, but the water comes from plants instead of open water like oceans or lakes. Together they are called evapotranspiration.
Is the water we drink today the same as ancient water?
Yes. Because water is recycled forever in the cycle and never used up, the water you drink has been around for billions of years. The very same molecules may once have been part of a prehistoric ocean, a dinosaur-era rainstorm, or a glacier.
