Natural water cycle

The natural water cycle is the continuous movement of water around the world through the processes of evaporation, transpiration, condensation, precipitation, run-off, infiltration and percolation.

Natural water cycle process


 


What happens in the natural water cycle?

The natural water cycle uses physical processes to move water from the surface of the earth to the atmosphere and back again.

  • Evaporation is when the sun shines on water and heats it, turning it into gas called water vapour which rises into the air.
  • Transpiration is when the sun warms people, plants and animals and they release water vapour into the air.
  • Condensation is when the water vapour in the air cools and turns back into a liquid, forming tiny water droplets in the sky.
  • Precipitation is when water droplets fall from the sky as rain, snow or hail.
  • Run-off is when water flows over the ground and into creeks, rivers and oceans.
  • Infiltration is when water falls on the ground and soaks into the soil.
  • Percolation is when water seeps deeper into tiny spaces in the soil and rock.

Water is continually moving through the natural water cycle.

Earth has exactly the same amount of water as it had thousands of years ago. This cycle is also called the hydrological cycle.

We modify and manage part of the natural water cycle to provide humans with water. This is called the urban water cycle.

  • The total amount of water on earth is 1,386 million km3
  • Water covers about three quarters of the earth’s surface.
  • 96% of the world’s water is saltwater. 
  • 3% is of the world’s water is freshwater, but most of it is frozen or not easy to get.
  • Less than one per cent of the world’s fresh water is useable.

Water on Earth graph

Less than 1% of the water on earth is useable for drinking.

Water is the most common substance found on earth. It's the only substance found naturally in three forms – solid (as ice), liquid (as water) and gas (as water vapour).

Water is made up of tiny molecules. One water molecule, called H2O, is made up of three atoms - two hydrogen atoms and an oxygen atom. These atoms stick together due to electrical energy.

Water is a solvent, which means it dissolves things. Wherever it travels, water carries chemicals, minerals and nutrients with it. This means water is more than what we can see.

There is a fixed amount of water on earth and it's constantly moving from one place to another in a process called the water cycle.

Want to make your own cloud?

Cloud in the sky

Try this experiment to make your own cloud and see how evaporation, condensation and precipitation works.

Safety first! You need adult supervision for this experiment.

Make a cloud