The water cycle in a tank
Shine a lamp on water in a covered tank with ice on the lid. Watch evaporation, condensation and rain happen in a small model of the water cycle.
Core concept
The Sun drives the water cycle of evaporation, condensation and precipitation
Topic: Water and the environment
Water on Earth moves round and round in the water cycle. The Sun heats seas, rivers and lakes, and water evaporation: When a liquid slowly turns into a gas (vapour), like puddles drying in the sun. All key words into the air as vapour. High up, the air is cold, so the vapour condensation: When a gas cools and turns back into a liquid, like drops on a cold glass. All key words into tiny droplets that make clouds. When the droplets join and grow heavy, they fall as rain, and the water flows back to rivers and seas. This tank is a small model of that cycle.
What you will learn
- Name the stages of the water cycle: evaporation, condensation and precipitation.
- Explain the role of the Sun's heat in the water cycle.
- Relate each part of the model to the real water cycle.
Before you start
- Know what evaporation and condensation are. Try "Evaporation and condensation" first.
Materials
- Water
- Ice
Equipment
- Clear tank with a lid
- Lamp
- Thermometer
Procedure
- The tank holds water. Its lid has ice on top, like cold air high in the sky.
- Switch on the lamp (the Sun) and watch the underside of the lid.
- Use the timer and watch what the droplets do.
- Switch the lamp off and see what happens to the rain.
How this simulation is simplified
- The model is sealed, so no water is lost. The Earth's water cycle is also a closed loop.
- Times are shortened. A real tank takes much longer to produce 'rain'.