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 our planet in many ways. This is called the water cycle. Water is found in many places. It is found on land. It is in the oceans and up in the air. Water comes in three forms. It exists as a solid, liquid or vapor.

Ice is solid water. Most freshwater on Earth is ice. It is found in big chunks called glaciers.

As ice melts, it turns to liquid. Water in a glass is liquid.

Water vapor is a gas. You cannot see gas. It is in the air around us.

The water cycle is made up of three parts:


Evaporation is when a liquid changes to a gas. Liquid water is found in seas, lakes or rivers. The sun warms up the water and the water turns into gas. It becomes water vapor. It goes up into the air. The planet is surrounded by gases. It is called the atmosphere.


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


After condensation, liquid or solid water falls to Earth. Precipitation is what falls. Rain and snow are precipitation. This is how water moves from the atmosphere to Earth.

How The Water Cycle Affects Our Planet

Humidity 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, like deserts, are different. They are not humid.

The water cycle can change how the land looks. Glaciers grow slowly. They can push up mountains. Rivers can wash away land. They can make big 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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