The water cycle round and round
Water never disappears. It moves round and round in the water cycle. First, the Sun warms the water in seas, rivers and puddles. Some of it evaporates: it changes into a gas called water vapour, which we cannot see, and rises into the air. High in the sky the air is cooler. The water vapour cools and condenses: it changes back into tiny drops of water that gather to make clouds. When the drops in a cloud join and grow big, they fall as rain. Rain, snow and hail are called precipitation. Some rain runs over the ground into rivers and the sea. Some soaks into the ground and becomes groundwater, which can come up again at a spring, like in an oasis. Then the Sun warms the water again and the cycle starts once more. When you study this, never look at the Sun.
| Stage | What happens | Example |
|---|---|---|
| evaporation | liquid water becomes vapour | a puddle dries |
| condensation | vapour cools into drops | a cloud forms |
| precipitation | water falls from clouds | rain |
| groundwater | water soaks into the ground | a spring in Siwa |
Water cycle in a bag, with a grown-up. Pour a little water (about a quarter of a cup) into a clear zip bag, seal it and tape it to a window that gets sunshine. Do not look at the Sun. Draw the bag in the morning, at noon and later in the day. What do you see on the inside? Then draw your own water cycle with the four words and arrows. Ask a partner to explain it back to you.