The Water Cycle
Evaporation and Condensation: The Water Cycle
The Water Cycle
The Water Cycle
What you'll learn
- The water cycle is the continuous journey of water between the oceans, land, and the atmosphere.
- Four main steps: evaporation (water rises as vapour), condensation (vapour cools into clouds), precipitation (rain, snow, or hail falls), and collection (water gathers in rivers, lakes, and oceans).
- The water cycle repeats endlessly, powered by heat from the Sun.
- To connect evaporation and condensation topics into one complete natural cycle.
Key concepts
Level 1 — The four main steps
Verbal: The Sun heats water in oceans, rivers, and lakes, causing evaporation. The vapour rises, cools, and condenses into clouds. When droplets in clouds become heavy enough, they fall as precipitation (rain/snow). This water collects in rivers, lakes, and oceans, ready to evaporate again.
Symbolic: Evaporation → Condensation → Precipitation → Collection → (repeat).
| Step | What happens | Where you see it |
|---|---|---|
| Evaporation | Water turns to vapour from heat | Ocean, lake, river surfaces |
| Condensation | Vapour cools into tiny droplets | Clouds forming in the sky |
| Precipitation | Droplets fall as rain, snow, or hail | Rainfall, snowfall |
| Collection | Water gathers in water bodies | Rivers, lakes, oceans, groundwater |
Everyday link: Rain falling today may be water that evaporated from a faraway ocean days earlier.
Level 2 — Why the water cycle keeps going
Verbal: The Sun's heat energy powers the whole cycle by driving evaporation; gravity pulls condensed water back down as precipitation. Since the Sun keeps shining, the cycle never stops.
Real-life: Plants also add water vapour to the air through a process called transpiration (water vapour released from leaves), adding to the water cycle alongside evaporation from oceans and lakes.
| Driving force | Role in the water cycle |
|---|---|
| Sun's heat | Powers evaporation from oceans, lakes, rivers |
| Cooling air at height | Causes condensation into clouds |
| Gravity | Pulls heavy droplets down as rain/snow |
| Rivers/streams | Carry collected water back toward oceans |
Worked example
Trace a single drop of ocean water through the water cycle back to the ocean.
Step 1 — Sun heats the ocean surface; the drop evaporates into water vapour.
Step 2 — Vapour rises, cools, and condenses into a tiny droplet inside a cloud.
Step 3 — The droplet joins others until it is heavy enough to fall as rain over land.
Step 4 — Rainwater flows into a river, which carries it back to the ocean.
Answer: The drop moves through evaporation, condensation, precipitation, and collection back to the ocean.
Why does the water cycle never run out of water?
Step 1 — Water only changes form and location; it is not created or destroyed.
Step 2 — Evaporation, condensation, and precipitation simply move the same water around endlessly.
Answer: The same water keeps cycling through the same four steps, so it never runs out.
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| Rain is "new" water made in the clouds | Missing the source of cloud water | Clouds form from evaporated water that was already on Earth, not newly created water |
| The water cycle only happens near oceans | Overlooking rivers, lakes, plants | Evaporation and transpiration happen from rivers, lakes, soil, and plants too |
| Water disappears forever after evaporating | Not tracing the full cycle | Evaporated water condenses and returns as precipitation |
| The cycle has a fixed starting point | Thinking in a straight line, not a loop | The water cycle is a continuous loop with no true beginning or end |
Quick check
- Name the four main steps of the water cycle in order.
- What powers evaporation in the water cycle?
- Why does rain eventually return to rivers and oceans?
- Stretch: How might cutting down a large forest affect the local water cycle?
Revision tip: Draw a simple circular diagram with arrows connecting evaporation, condensation, precipitation, and collection.
Open the Practice tab for graded questions on The Water Cycle.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
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