The Water Cycle
Water evaporates, condenses, precipitates and flows back.
About this topic
Water circulates through evaporation from oceans and lakes, transpiration from plants, condensation into clouds, precipitation as rain or snow, and runoff or infiltration back to rivers, groundwater and the sea. The Sun's energy drives it, and gravity pulls water downhill.
It redistributes fresh water and heat around the planet and supplies every living thing. About 97% of Earth's water is salty ocean, and most fresh water is locked in ice caps and glaciers, so only a tiny fraction is easily available. Plants play a big role: roots absorb water, and transpiration through stomata releases vapour, which can help create local rainfall.
Follow a single water molecule. It evaporates from the Pacific, rises and cools, condenses on dust particles into a cloud, falls as snow on a mountain, melts in spring, runs into a river, soaks into a field, is absorbed by a wheat plant and transpires back to the air. The cycle never creates or destroys water; it only moves it between stores.
Understanding the cycle helps manage reservoirs, floods, droughts and irrigation. Deforestation reduces transpiration and can change rainfall, while climate change alters how much falls as rain or snow. Remember that evaporation is not the same as boiling; it happens at any temperature from the surface of liquid water.
Key ideas
- Evaporation and transpiration
- Condensation forms clouds
- Runoff returns water
Quick check
Use cases: where The Water Cycle helps
- Homework: review the key idea behind The Water Cycle before you start a problem set.
- Exam revision: use the quick check to test whether you can recall The Water Cycle without notes.
- Visual learning: play with the interactive lab to see how The Water Cycle changes when you adjust its inputs.
- Teaching a friend: explain The Water Cycle in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is The Water Cycle?
Water evaporates, condenses, precipitates and flows back.
What will I learn in The Water Cycle?
Evaporation and transpiration. Condensation forms clouds. Runoff returns water.
Is The Water Cycle part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the The Water Cycle lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study The Water Cycle?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.