जल चक्र
Water Cycle
The water cycle is the endless movement of water between the earth and the sky. Water evaporates from seas, rivers and land, condenses into clouds, falls as rain or snow, and flows back — so the total quantity of water on earth never changes, only its form and its place.
The stages
- Evaporation — the sun heats water and turns it into invisible water vapour.
- Transpiration — plants release water vapour from their leaves.
- Condensation — vapour rises, cools and turns into tiny droplets that form clouds.
- Precipitation — droplets join, become heavy and fall as rain, snow or hail.
- Collection and run-off — water gathers in rivers, lakes and seas, or soaks into the ground, and the cycle repeats.
Evaporation → Condensation → Precipitation → Collection
Three changes of state
| Change | Name | Everyday example |
|---|---|---|
| Liquid to gas | Evaporation | Wet clothes drying in the sun |
| Gas to liquid | Condensation | Water drops on a cold bottle |
| Liquid to solid | Freezing | Water becoming ice in a freezer |
| Solid to liquid | Melting | Ice melting into water |
| Liquid to gas at high heat | Boiling | Steam from a kettle |
Evaporation happens at any temperature and only at the surface; boiling happens at a fixed temperature throughout the liquid. This distinction is asked directly and candidates often miss it.
What speeds up evaporation
- More heat — clothes dry faster in the sun than in the shade.
- More surface area — spread clothes dry faster than bunched ones.
- More wind — a breeze carries the vapour away.
- Less humidity — clothes dry slowly on a rainy day because the air is already full of vapour.
Teaching it by experiment
Fill two saucers with the same amount of water, keep one in sunlight and one in shade, and record the level over a day. Or cover a plant's leaf with a polythene bag and watch the droplets that collect — transpiration made visible. Class 4 and 5 EVS prefers such small experiments to a labelled diagram, and CTET's pedagogy questions follow the same preference.
✗ The water on earth is reducing because so much evaporates. | ✓ The total quantity stays the same; the cycle returns it as rain.
✗ Evaporation and boiling are the same process. | ✓ Evaporation happens at any temperature from the surface; boiling happens at a fixed temperature throughout.
संकेत: वाष्पीकरण → संघनन → वर्षा → संग्रह; जल की कुल मात्रा वही रहती है, केवल रूप बदलता है।
The water cycle is asked once or twice, usually as the order of stages or the naming of a change of state. Transpiration is the stage candidates forget, so include it. The evaporation-versus-boiling distinction is a standing trap. A pedagogy version asks the best way to teach evaporation, and the correct answer is the two-saucer experiment with children recording observations, not the textbook diagram.
Frequently asked questions
What are the stages of the water cycle?
Evaporation from water bodies and land, transpiration from plants, condensation into clouds, precipitation as rain, snow or hail, and collection in rivers, lakes, seas and the ground, after which the cycle repeats.
What is the difference between evaporation and boiling?
Evaporation happens at any temperature and only from the surface of a liquid, while boiling happens at a fixed temperature and throughout the liquid, with bubbles forming inside it.
Why do clothes dry faster on a windy sunny day?
Because heat gives water molecules the energy to escape and wind carries the vapour away from the surface, keeping the air near the cloth dry so more water can continue to evaporate.
60-second recap
- Water cycle: evaporation, transpiration, condensation, precipitation, collection.
- Total water on earth stays constant; only its form and place change.
- Evaporation is from the surface at any temperature; boiling is throughout at a fixed one.
- Heat, surface area, wind and dry air all speed up evaporation.
- Teach with the two-saucer experiment, not a diagram.