Water is always changing states, from liquid to vapour to ice and back again.Â
What is always moving, whether it be in the sky, on the ground or underground.
This movement is called t'he water cycle' because water moves round and round.
The heat of the sun provides energy to make the water cycle work.
The sun evaporates water from the oceans into water vapour.
This invisible vapour rises into the atmosphere, where the air is colder.
The colder air causes water vapour to condense into water droplets and clouds.
In the atmosphere, air currents move clouds all around the Earth.
Water drops form in clouds, which then fall to Earth as precipitation (rain and snow).
In cold climates, precipitation builds up as snow, ice, and glaciers.
Snow can melt, becoming runoff, which flows into rivers, the oceans, and onWater is always movingto the ground.
Some ice evaporates directly into the air, skipping the melting phase (sublimation).
Rainfall on land flows downhill as runoff, providing water to lakes, rivers, and the oceans.
Some rain soaks into the ground, as infiltration, and, if deep enough, becomes groundwater.
Water from lakes and rivers can seep into the ground.
Water moves underground because of gravity and pressure.
Groundwater close to the land surface is taken up by plants.
Some groundwater seeps into rivers and lakes, and can flow to the surface as springs.
Plants take up groundwater and evapotranspire, or evaporate, it from their leaves.
Some groundwater goes very deep into the ground and stays there for a long time.
Groundwater flows into the oceans, keeping the water cycle going.
Water Cycle and Water Pollution
What is water contamination?
What is water scarcity?
What is water pollution?
Cambodia's water crisis
Cities in Asia are sinking
The Mekong river is dying
Southeast Asia and water
How Singapore solved its water problems
Singapore's water solutions
Singapore's sewage processing
How Singapore manages flooding
How far would you walk for water?
Wells as a source of water
Water cycle science for drinking water
Cleaning up the Klang River
Testing and cleaning Penang's riversÂ
Floods impact Malaysia national exams
Causes of pollution in Malaysia's rivers
How to make your own water filter using a plastic bottle
Thailand, building a water filter tank for a school