Natural water cycle

Water is constantly moving around

Did you know that all the water on Earth is all that we have? It's constantly moving around in a natural cycle. Some water is easy to see in our rivers and oceans, but some water is underground or in the atmosphere!


Natural water cycle processes

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

What happens in the natural water cycle?

The natural water cycle uses physical processes to continually move water from the surface of the Earth to the atmosphere and back again. This cycle is also called the hydrological cycle.

  • 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.

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


Properties of water

Did you know?

  • Water is the most common substance found on Earth. It's the only substance found naturally in 3 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 chemicalsminerals and nutrientswith it. This means water is more than what we can see.
  • Water can be tested to see if it is acidic, basic or neutral. We like our water around neutral so it doesn't corrode pipes and home appliances.

Water on Earth

Did you know?

  • Earth has exactly the same amount of water as it had thousands of years ago. 
  • 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 1% of the world’s fresh water is useable.

Water cycle experiments

Have you ever wondered how water evaporates? Where clouds come from or where water goes after it rains? It’s all part of the water cycle.

Try these science experiments to see for yourself.


Atmosphere

Gases that surround a planet, like the air that surrounds Earth.

Hydrological cycle

The cycle of water between the Earth and the atmosphere powered by the Sun. Also called the water cycle.

Urban water cycle

The urban water cycle is the way water is collected, used and managed in an urban environment such as Sydney.

Molecules

A group of at least two atoms held together by strong chemical bonds.

Atoms

A basic unit of matter consisting of a central nucleus surrounded by negatively charged electrons.

Chemicals

A substance made up of specific elements.

Minerals

A solid substance formed through geological processes that has a specific chemical composition, structure, and physical property.

Nutrients

A substance that provides nourishment, food or energy.