The Water Cycle
The water cycle describes how water moves continuously between the Earth's surface and the atmosphere. The same water has been cycling on Earth for billions of years!
1. Evaporation
The sun heats water in oceans, rivers, and lakes. The water turns into water vapour (a gas) and rises into the air. This is evaporation.
Also: plants release water vapour in a process called transpiration.
2. Condensation
As water vapour rises, it cools down. Cool air can't hold as much water vapour, so it turns back into tiny water droplets. These form clouds.
Example: you can see condensation on a cold glass on a warm day.
3. Precipitation
When water droplets in clouds join together and become heavy, they fall back to Earth as precipitation: rain, hail, sleet, or snow.
In Australia, precipitation is usually rain. In alpine areas, snow falls in winter.
4. Collection and Runoff
Water that falls on land collects in rivers, lakes, and groundwater. It also runs off into the ocean. The sun heats it up again — and the cycle repeats!
Water also soaks into the ground — this is called infiltration.
The Cycle in Order
Evaporation
water → vapour
Condensation
vapour → clouds
Precipitation
clouds → rain
Collection
water returns
The cycle is continuous — water is never created or destroyed, just moved!
Key Vocabulary
Knowledge Check
Question 1
What happens during evaporation?
Question 2
How do clouds form?
Question 3
Rain, hail, sleet, and snow are all examples of what?
Question 4
Why is the water cycle called a "cycle"?
Lesson Summary
- ✓The water cycle is the continuous movement of water between the Earth's surface and atmosphere.
- ✓Evaporation: the sun heats water → it becomes water vapour and rises.
- ✓Condensation: water vapour cools → forms tiny droplets → clouds.
- ✓Precipitation: water falls from clouds as rain, hail, or snow → collects in rivers and oceans → and the cycle begins again.