The water cycle

Water is a key compound for life on Earth.

Water is important for:

Some organisms can survive in a dormant state without water for long periods of time, but all organisms will quickly or eventually die without it.

The is easiest to understand in terms of its processes and what happens to the water in each stage.

Process	What happens to water
Evaporation	Water turns from a liquid to a gas when it evaporates. Energy from the Sun can evaporate water from all places on the Earth's surface such as puddles, ponds, lakes and oceans.
Condensation	After evaporation, water can cool and convert from gas to liquid, often forming clouds.
Transport	Water within clouds can be blown many miles by strong winds and so is transported to other areas.
Precipitation	Precipitation occurs when rain, snow, hail and sleet fall from the sky.
Surface runoff	Much water will be absorbed into the ground after precipitation but if a large volume falls or the ground is already wet then some water can run along the surface of the ground.
Infiltration	This occurs when water that has fallen as precipitation is absorbed into the ground. This can then be stored within underground rocks called aquifers.
Transpiration	Plants need to maintain a constant stream of water to their leaves for photosynthesis, support and transport of minerals. They allow some water to evaporate as water vapour from their leaves so that more water is continuously 'pulled' to their leaves from the soil.

Process	Evaporation
What happens to water	Water turns from a liquid to a gas when it evaporates. Energy from the Sun can evaporate water from all places on the Earth's surface such as puddles, ponds, lakes and oceans.

Process	Condensation
What happens to water	After evaporation, water can cool and convert from gas to liquid, often forming clouds.

Process	Transport
What happens to water	Water within clouds can be blown many miles by strong winds and so is transported to other areas.

Process	Precipitation
What happens to water	Precipitation occurs when rain, snow, hail and sleet fall from the sky.

Process	Surface runoff
What happens to water	Much water will be absorbed into the ground after precipitation but if a large volume falls or the ground is already wet then some water can run along the surface of the ground.

Process	Infiltration
What happens to water	This occurs when water that has fallen as precipitation is absorbed into the ground. This can then be stored within underground rocks called aquifers.

Process	Transpiration
What happens to water	Plants need to maintain a constant stream of water to their leaves for photosynthesis, support and transport of minerals. They allow some water to evaporate as water vapour from their leaves so that more water is continuously 'pulled' to their leaves from the soil.

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