Water Cycle

The Water Cycle or the Hydrological cycle is how water moves around the Earth. It has seven stages, including evaporation, condensation, sublimation, precipitation, transpiration, runoff, and infiltration. The water cycle begins when water vapor forms clouds, and this causes it to rain or snow when the conditions are right.

It is called a cycle because it is basically a circle where things continue to happen over and over.

water cycle

One part of the water cycle is that water that is on the surface of the lake or the ocean will eventually evaporate and when water evaporates, it turns into water vapor.

The water vapor then goes into the clouds.

As the clouds move around the Earth, they pick up water vapor and when they get full, they begin to drop water, which is called rain (Rainfall) or snow (Snowfall).

When the water hits the Earth, it can fall on the ground, in the ocean, it can be on the mountains or it can fall onto plants and trees and help to feed them.

After the water hits the Earth, it begins to evaporate, which causes water vapor to move into the clouds and stays there until the clouds get full.

This is why it is basically a big circle that never ends and helps life on earth.

Water Cycle Facts for Kids:

  • 68% of the world’s fresh water is held in ice caps and glaciers
  • 71% of the planet surface is covered by water
  • 60% of the adult human body is water
  • Humans can only survive without water for about three days
  • The rain that falls from the clouds is called precipitation.
  • Other planets have rain too.
  • Venus has rain that is made of acid.
  • We store water in a reservoir
  • Weather radar helps to monitor the amount of rain to an area.
  • When there is too much rain, it can cause flooding.
  • Antarctica is the driest continent.
  • When a lot of rain falls in a forest, it is called a rainforest.
  • The rain that has high levels of acid is called acid rain and can be harmful to people, animals, and plants.
  • Water can change directly from a solid to a gas without turning into a liquid.  This is called sublimation.
  • Ice can go directly to the clouds without melting.

How Does Water Get into the Atmosphere?

Transpiration of rice leaves

There are three ways that water gets into the atmosphere:

  • Sublimation
  • Evaporation
  • Transpiration

Sublimation happens when water goes immediately to vapor from ice or snow without it even melting. This can happen when there is a lot of snow or a lot of ice and it is very cold.  But it has to be sunny so that the ice can turn into vapor.

Evaporation (Evapotranspiration) happens when surface water goes from the ground to the air.  Around 90% of this groundwater vapor that is found in the atmosphere happens because of evaporation.  Evaporation only is present on the water’s surface, but it also takes in energy from the heat of the sun.  When water vapors are warmed, they evaporate easier than when they are cold.  The sun is the main reason for evaporation.

Transpiration happens when plants give off the water on their leaves and then the water on their leaves evaporates and turns into a vapor.  Plants release a lot of water as they grow.

Rain and Precipitation

Raining cloud over a field in summer farmland

There is a lot of water that is in the atmosphere and in the clouds.

When the clouds get full, the precipitation falls to the ground.  The precipitation is water that was taken into the clouds and then falls back to the land.

Water vapor comes in the form of:

  • Rain
  • Snow
  • Hail
  • Sleet

Important Words to Know About the Water Cycle:

  • Evaporation-when there is heat from the sun that causes water on the Earth to turn into gas and go into water vapor and moves to the clouds.
  • Condensation-when water that is in the clouds cools and then becomes water again.
  • Collection-Water that evaporates from the lakes, oceans or rivers, goes into the clouds, falls as precipitation, and then goes back into the cycle.


When the sun heats up the water that is on the surface of the Earth, the water will turn into gas vapors that go into the air.  These vapors come from oceans, lakes, streams and rivers, and even plants and trees.

When plants and trees lose their water, it is through their leaves.  This is called transpiration.


When the vapors go into the air, it gets cooler and they turn from a gas to a liquid and it causes there to be clouds.

The clouds move all around the world.


When there is a lot of water that has condensed, clouds can become big and heavy.

The water in the clouds is so heavy that the air can no longer hold it and the water goes back down to the Earth.


When the water that comes from the clouds fall from the sky, the precipitation is collected.

This collection happens in rivers, oceans, lakes, or other bodies of water.

Some of the water falls right back into the bodies of water where some will fall on plants and vegetation.

When the water is collected in the bodies of water, it starts the water cycle over and will once again begin to evaporate.

When the water is collected by plants and vegetation, the water will start the water cycle again by evaporating from the leaves of the plants.

If the weather is super cold, the precipitation can be snow or ice.  When the snow or ice melts when the temperatures are higher, it will turn to water and begin the water cycle again.

Surface Runoff

When there is water that goes to the ground and it gets so high that it goes along the ground and it is called surface runoff.

When this happens, the precipitation soaks into the soil and it will move through the ground until it reaches a body of water such as the ocean, a lake, or a river.

What is Interesting About the Water Cycle?


One thing that is interesting about the water cycle is that water goes through a system that always is moving and water can come in different forms such as:

  • Liquid
  • Gas
  • Solid

When the water goes through the continuous cycle, remember that it has been doing this for over 4 billion years.

Where is Most of the Water on the Earth Found?

Water is stored all over the atmosphere of the Earth including:

  • Oceans
  • Lakes
  • Ice on the mountain tops
  • In glaciers
  • Underground

Why is the Water Cycle Important?

Watering garden

The water cycle is important because people need drinking water and plants and vegetables need water in order to grow.

Water flows into the water supply so we can have drinking water and other domestic uses.

Animals also need water, so the continuous movement of the water is important for all living things.

What causes Drought

In some countries, as temperatures rise, it can cause an increase of evaporation, you then have no soil moisture as it can dry out.

When it rains, the water runs into the rivers and streams because the ground is hard.

The result? You get more evaporation and risk of drought.

How is Water in the Atmosphere Studies?

Jason-3 satellite – Meteorological Satellite

NASA uses something called a CloudSat to study water that forms into clouds.  The CloudSat gets information about the clouds and how they move and change the weather.

Another way that NASA studies water is through the GPM or the Global Precipitation Measurement Mission.

This helps scientists to know how much it rains and snows on the Earth.

Jason-3 (picture above)  is used to check the sea level and the temperature of the oceans.

The Grace-Fo or the Gravity Recovery and Climate Experiment-Follow On-watches water as it moves from one place to the other.

It measures how deep the groundwater is below the surface of the Earth.

The Aqua satellite tells about water that is in the oceans, the land, how much snow and ice cover the Earth, and the sea.

What Did You Learn?

  • What is the water cycle?  The water cycle is the process of the water going from bodies of water into the atmosphere and then into the land.  This is a continuous system that is always moving.
  • What are the three ways that water gets into the atmosphere?  The water gets into the atmosphere through sublimation, evaporation, and transpiration.
  • What are the three forms that water can come in?  Water can come in a liquid, a solid or a gas.
  • What is surface runoff?  Surface runoff is when water flows along the ground until it reaches a body of water where it can begin the water cycle again.
  • What is evaporation?  Evaporation is when heat from the sun causes the water to turn into a vapor and move into the atmosphere as a cloud.