Hydrologic Cycle

Hydrologic Cycle

The water cycle describes how water is exchanged (cycled) through Earth's land, ocean, and atmosphere.


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Earth Science, Meteorology, Geography, Physical Geography, Geology

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Water moves through Earth on the land, oceans and air. This is called the water cycle. Water always exists in all three places, in many forms.

Evaporation, Condensation And Precipitation

The water cycle is made up of three major parts: evaporationcondensation and precipitation.


Evaporation is when a liquid changes to a gas. A liquid is something that flows, like water in a river. A liquid is not hard like a rock. A rock is a solid. Liquid water is found in the ocean, lakes or rivers. This water evaporates and becomes water vapor. It is a gas that you cannot see. It goes up into the air. The air around the planet is called the atmosphere.

Evaporation is caused by the sun. The sun warms up the water and the water turns into gas.


Condensation is when gas changes to a liquid. This happens to water vapor in the atmosphere. The gas cools down and it turns into liquid.


After condensation, liquid or solid water falls to Earth. Precipitation is what falls. Rain and snow are precipitation.

Precipitation is important in the water cycle. It is how water moves from the atmosphere back to Earth.

States Of Water

Water comes in many forms and continually changes in the water cycle. Water is in three forms. They are solid, liquid and vapor.

Ice is solid water. It is hard like a rock. Most of Earth's freshwater is found in giant mountains of ice called glaciers.

As ice melts, it turns to liquid. The ocean, lakes and rivers hold liquid water.

Water vapor is in the atmosphere. There is a lot of water vapor above the ocean. There is very little in the air above deserts where it is very dry.

The Water Cycle And Climate

The water cycle has a big effect on climateClimate is the kind of weather in an area.

Humidity creates different climates on Earth. It is how much water vapor is in the air. Places on the coast are very humid. There is a lot of water vapor in the atmosphere. Places far away from water are not humid.

The Water Cycle And The Landscape

The water cycle also affects the land on Earth.

As glaciers slowly grow, they can carve out valleys. Glaciers can push up mountains. Rivers can carve huge canyons.

Fast Fact

Breaking the Cycle
The water cycle can change. Glacial retreat is the process in which glaciers melt faster than their ice can be replaced by precipitation. Glacial retreat limits the amount of fresh water available on Earth. We are experiencing the fastest rate of glacial retreat in recorded history.

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Jeannie Evers, Emdash Editing, Emdash Editing
National Geographic Society
Last Updated

October 19, 2023

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