The Water Cycle in Detail
Describe the water cycle, tracing water through evaporation, condensation, precipitation, surface runoff, and transpiration in plants, explaining how the sun drives the cycle
What a learner can do afterwards
- Labels a water cycle diagram correctly
- Explains what drives each stage of the water cycle (e.g. solar energy drives evaporation)
- Explains the role of transpiration (plants releasing water vapour) in the water cycle
- Discusses how human activities (deforestation, paving) affect the water cycle
1 · Read
Water never disappears. It just changes shape and place, moving through a loop called the water cycle. Five stages carry it around: evaporation, condensation, precipitation, surface runoff, and transpiration. One thing powers the whole loop: heat from the sun. That heat does not vanish at sunset, because the oceans and the air hold on to it, so the cycle keeps turning at night.
Two paths add extra water to the loop. Surface runoff is rain that flows over the ground into rivers, lakes, and the sea instead of soaking in. Transpiration is water vapour escaping through tiny pores in plant leaves, joining the vapour already rising from oceans and lakes.
A raindrop lands on a forest hillside. Some of it sinks into the soil. The rest becomes surface runoff, trickling downhill into a stream. Nearby, a tree pulls water up through its roots and releases some back into the air through its leaves: transpiration. Both paths send water back toward the sky or the sea, ready to evaporate again.
Human activity changes the cycle. Cutting down forests removes trees that would have released water vapour through transpiration. Paving ground with roads and car parks stops rain soaking in, so more of it runs off fast instead of slowly returning to rivers and the water table.
The sun powers a nonstop loop: water evaporates, condenses, falls as rain, runs off the land, and returns from plant leaves through transpiration.
2 · Watch
Take it off screen
Where it sits
Learn first
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.