The Hydrologic (Water) Cycle
Introduced| English |
|---|
| precipitation/prɪˌsɪpɪˈteɪʃn/ |
| evaporation/ɪˌvæpəˈreɪʃn/ |
| transpiration/trænspəˈreɪʃn/ |
| condensation/kɒndenˈseɪʃn/ |
Water on an endless journey
- The water you drink today has been around for billions of years.
- It is never made or destroyed — only recycled.
- The same water moves from sea to sky to land and back.
- This endless journey is the water cycle, powered by the Sun.
Evaporation lifts water up
- The Sun heats the oceans, lakes, and rivers.
- Through evaporation 蒸发, liquid water turns into invisible water vapour.
- The vapour rises into the atmosphere.
- Plants add more vapour through transpiration 蒸腾作用 from their leaves.
What provides the energy that drives the water cycle?
The Sun heats water and powers evaporation, driving the whole cycle.
Evaporation turns…
Evaporation changes liquid water into gas (vapour) that rises into the air.
Condensation makes clouds
- As vapour rises, it cools.
- Through condensation 凝结, it turns back into tiny liquid droplets.
- Billions of droplets together form clouds.
- The water is now high in the sky, waiting to fall.
The water cycle
Step around the cycle - the Sun drives water from the surface into the air and back as rain.
Water falling back to Earth as rain or snow is called ____.
Precipitation is water returning to the surface as rain, snow, or hail.
Precipitation returns it
- When droplets grow heavy, they fall as precipitation 降水 — rain or snow.
- The water collects in rivers, lakes, and the ground.
- It flows back toward the sea as runoff.
- There the Sun evaporates it again, and the cycle repeats.
Plants also add water vapour to the air through transpiration.
Transpiration is water evaporating from plant leaves — a big source of vapour over land.
Select all true statements about the water cycle.
Water is recycled, never created or destroyed. The other three are correct.
Water is recycled, not created or destroyed. The total amount of water on Earth stays about the same; the cycle just keeps moving it around. So when we "use up" fresh water, we really mean it has moved somewhere hard to reach or become polluted — not that it vanished.
A raindrop's round trip:
- Sunlight evaporates a drop of seawater into vapour.
- It rises, condenses into a cloud, and falls as rain onto a mountain.
- It flows down a river back to the sea — completing one loop of the water cycle.
The water cycle, driven by the Sun, recycles Earth's water. Evaporation (and plant transpiration) lift water vapour up; condensation forms clouds; precipitation returns water as rain or snow; and runoff carries it back to the sea. Water is recycled, never created or destroyed.