🎒 Base knowledge and understanding

✅ Tasks

🌿 Content

🔑 Key terms

Phase 1

Where is Earth's water?

Imagine you have a 1 litre bottle that contains all the water on Earth. You then have to share that water out into six containers, each representing one of the main water stores:

Oceans
Glaciers and ice caps
Groundwater
Surface freshwater (lakes, rivers, swamps)
Atmosphere (water vapour and clouds)
Organisms (water inside all living things)

Without looking anything up, predict the percentage of the litre that goes into each container. Your six numbers must add up to 100%.

Write your six predictions here.
Once your teacher reveals the actual values, calculate the difference between your prediction and the actual value for each store. Which one were you furthest off?

Roughly 97% of all water on Earth is salt water. What does this imply about how much of the world's water is realistically available for drinking, agriculture and industry? Write 2 sentences.

Phase 2: What drives the water cycle?

Solar radiation and gravity

4.1.1 Movements of water in the hydrosphere are driven by solar radiation and gravity.

Heat is required for evaporation of water and is released when water condenses. Gravity causes water to drain through soil and in rivers to the sea.

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Two forces move every drop of water on Earth.

Solar radiation provides the energy needed to lift water into the atmosphere. Heat from the Sun causes liquid water to evaporate and ice to sublime. This energy is not lost: it is stored in the water vapour and is released again when the vapour condenses higher in the atmosphere. This is one of the main ways the Sun's energy is redistributed around the planet.

Gravity does the opposite. It pulls condensed water back to the surface as precipitation, drags surface water downhill in rivers, and pulls infiltrating water downwards through soil and rock.

Without solar radiation, water would never leave the surface. Without gravity, it would never come back. The cycle exists because the two forces are constantly opposing each other.

State the two forces that drive the hydrological cycle.
Explain why the Sun is needed for evaporation but not for precipitation.
The energy used to evaporate water is released again later when the water vapour condenses. Suggest one consequence of this for the global climate system. (Hint: think about where evaporation happens versus where condensation happens.)

🎒 Base knowledge and understanding

✅ Tasks

🌿 Content

🔑 Key terms

Phase 1

Where is Earth's water?

Write your six predictions here.

Once your teacher reveals the actual values, calculate the difference between your prediction and the actual value for each store. Which one were you furthest off?

Roughly 97% of all water on Earth is salt water. What does this imply about how much of the world's water is realistically available for drinking, agriculture and industry? Write 2 sentences.

Phase 2: What drives the water cycle?

Solar radiation and gravity

State the two forces that drive the hydrological cycle.

Explain why the Sun is needed for evaporation but not for precipitation.

The energy used to evaporate water is released again later when the water vapour condenses. Suggest one consequence of this for the global climate system. (Hint: think about where evaporation happens versus where condensation happens.)