The Water Cycle

Water

Water is one of our most important resources. All living things need water to survive. In fact, many types of plants and animals actually live in water. We have to drink water to stay alive. We also use water to bathe, cook, water our plants and wash things like dishes, clothes and cars. Lucky for us, our planet has lots of water.

Did you know that the water on Earth has been around for millions of years? It just keeps moving around and it gets reused over and over again. To understand how this happens we need to study the water cycle.

What is the Water Cycle?

The movement of water from the Earth’s surface to the atmosphere and back again is called the water cycle.

Water often moves from one place to another. Water in a river may flow into the sea or a lake. Water evaporates from the land or sea and goes into the atmosphere. Clouds are made up of tiny water droplets floating in the atmosphere. Water sometimes falls from clouds as rain or snow. All of these things are part of the water cycle.

How does the water cycle work?

The water cycle is powered by heat from the sun. There are four main stages in the water cycle. They are evaporation, condensation, precipitation and collection. Let us look at each one.

Evaporation: The sun heats up the surface of the sea or the land. This causes water to change into water vapour and rise into the atmosphere. This is called evaporation.

Condensation: As the water vapour rises high into the atmosphere, it cools down. This causes it to turn back into droplets of water. This is called condensation. When water vapour condenses in the atmosphere, it forms clouds.

Precipitation: Inside the cloud, small water droplets may join together to form bigger droplets. Then they fall as rain, snow or even hail. This is called precipitation.

Collection: When water falls to the ground, it collects in various places. Some of it falls into the oceans, seas or lakes. Some of it falls onto the land and runs into streams and rivers. Some water enters the soil and is stored in the ground. This water is called groundwater.

Take a look at the diagram of the water cycle below.