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Tracing the water cycle

Science · Ecosystems & Habitats · ages 11-12

Name ______________________ Date ____________

Which source supplies most of the energy driving Earth's water cycle?
- Wind heating the oceans
- Solar energy from the Sun
- Heat supplied by the Moon to Earth's oceans
Which process changes liquid water into water vapour?
- Evaporation
- Precipitation
- Condensation
All rainwater must flow over the ground into a stream before it can return to the air.
Circle one: True False
A grassy field is covered with sealed asphalt for a car park. With the same rainfall, what is likely to happen?
- More rain soaks in
- More rain runs off across the surface
- Evaporation stops across the whole car park
Follow the water pathway shown. Which processes belong in A, B and C, in that order?
- Condensation, evaporation, precipitation
- Evaporation, precipitation, condensation
- Evaporation, condensation, precipitation
Water taken up by tree roots later leaves the tree as vapour through leaf pores. Which process releases this vapour?
- Transpiration
- Precipitation
- Runoff
A hillside forest is replaced with sealed roads. After storms with similar rainfall, streams below rise more quickly. Which explanation best fits?
- Sealed roads limit infiltration, so runoff arrives sooner
- Fewer trees transpire, so storm runoff speeds up
- Sealed roads allow more infiltration, so soil water reaches streams sooner
Ben says evaporation and falling rain need direct sunlight. After sunset, a warm pond still loses water as vapour and rain falls nearby. Which explanation accounts for both?
- Stored heat supports evaporation; cooling makes the rain fall
- Gravity powers evaporation; gravity pulls rain down
- Stored heat supports evaporation; gravity pulls rain down

Answer key

For grown-ups. Fold this page away before handing over the rest.

Tracing the water cycle W1-mt_V2lNzEex_a-s1

Solar energy from the Sun · The Sun supplies solar energy that supports evaporation. Gravity also moves water down through the cycle.
Evaporation · Evaporation changes liquid water into water vapour. Condensation changes vapour back into liquid droplets.
False · Rainwater can evaporate from wet surfaces. It can also soak into soil, enter plants and return through transpiration without first reaching a stream.
More rain runs off across the surface · Sealed asphalt limits infiltration, so a larger share of rain is likely to become surface runoff.
Evaporation, condensation, precipitation · A is evaporation, liquid becoming vapour. B is condensation, vapour forming droplets. C is precipitation, water falling from clouds.
Transpiration · Transpiration releases water vapour through leaf pores, connecting soil water, plants and the air.
Sealed roads limit infiltration, so runoff arrives sooner · Sealed roads limit infiltration, sending more water towards streams as surface runoff. Tree removal can reduce transpiration, but that is not the main immediate cause of the quicker storm response.
Stored heat supports evaporation; gravity pulls rain down · Stored heat can support evaporation after sunset. Gravity pulls rain down. Cooling can allow condensation, but it does not provide the downward pull on rain.