Matter goes round
Show on a big screenRain falls from clouds that were once part of the sea.
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The rule
Vapour is water as a gas. Evaporates means turns into vapour. Condenses means turns back to liquid.
Water evaporates, condenses, falls, then flows on. The Sun drives this round.
- The Sun warms the sea, and water evaporates into vapour.
- The vapour rises and cools, forming clouds.
- Clouds release the water as rain.
- Rain runs off the land and collects back in rivers and the sea.
The idea
Matter does not vanish. It moves in loops between living and non-living parts of Earth. These loops are biogeochemical cycles. Water, carbon, nitrogen and oxygen all go round.
Picture a village tank in Tamil Nadu. The Sun warms it, and water becomes vapour. The vapour rises, cools and forms clouds. Monsoon rain fills the tank again.
Some rain soaks into the soil. A coconut palm takes up that water through its roots. Its leaves let the water out as vapour. That last step is transpiration.
| Step | What happens |
|---|---|
| Evaporation | Liquid water becomes vapour |
| Condensation | Vapour cools and forms clouds |
| Precipitation | Rain, hail or snow falls |
| Infiltration | Water seeps into the soil |
| Run-off | Water flows over the land |
| Transpiration | Leaves let out water vapour |
Warm air holds more vapour, so storms can drop heavy rain. Hard rain runs off the land before it can soak in. Less water then refills the groundwater. Groundwater is water stored under the ground.
Try the lab to finish this lesson.