Encyclopedic Entry

Catch a wave, and you're sitting on top of the hydrosphere.

Photograph by Jason Kampf, MyShot

Hydrosphere in Space
Some scientists believe a hydrosphere exists on Europa, a moon of Jupiter, that consists of a frozen outer layer and a giant, liquid ocean underneath it.

A hydrosphere is the total amount of water on a planet. The hydrosphere includes water that is on the surface of the planet, underground, and in the air. A planet's hydrosphere can be liquid, vapor, or ice.

On Earth, liquid water exists on the surface in the form of oceans, lakes and rivers. It also exists below ground—as groundwater, in wells and aquifers. Water vapor is most visible as clouds and fog.

The frozen part of Earth's hydrosphere is made of ice: glaciers, ice caps and icebergs. The frozen part of the hydrosphere has its own name, the cryosphere.

Water moves through the hydrosphere in a cycle. Water collects in clouds, then falls to Earth in the form of rain or snow. This water collects in rivers, lakes and oceans. Then it evaporates into the atmosphere to start the cycle all over again. This is called the water cycle.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

aquifer

Noun

an underground layer of rock or earth which holds groundwater.

Encyclopedic Entry: aquifer

atmosphere

Noun

layers of gases surrounding a planet or other celestial body.

Encyclopedic Entry: atmosphere

cloud

Noun

visible mass of tiny water droplets or ice crystals in Earth's atmosphere.

Encyclopedic Entry: cloud

cryosphere

Noun

icy part of the Earth's waterincluding icebergs, glaciers, and ice caps.

Earth

Noun

our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.

Encyclopedic Entry: Earth

Europa

Noun

moon of Jupiter.

evaporate

Verb

to change from a liquid to a gas or vapor.

fog

Noun

clouds at ground level.

Encyclopedic Entry: fog

glacier

Noun

mass of ice that moves slowly over land.

Encyclopedic Entry: glacier

groundwater

Noun

water found in an aquifer.

Encyclopedic Entry: groundwater

hydrosphere

Noun

all the Earth's water in the ground, on the surface, and in the air.

Encyclopedic Entry: hydrosphere

ice

Noun

water in its solid form.

Encyclopedic Entry: ice

iceberg

Noun

large chunks of ice that break off from glaciers and float in the ocean.

Encyclopedic Entry: iceberg

ice cap

Noun

area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.

Encyclopedic Entry: ice cap

Jupiter

Noun

largest planet in the solar system, the fifth planet from the Sun.

lake

Noun

body of water surrounded by land.

liquid

Noun

state of matter with no fixed shape and molecules that remain loosely bound with each other.

ocean

Noun

large body of salt water that covers most of the Earth.

Encyclopedic Entry: ocean

planet

Noun

large, spherical celestial body that regularly rotates around a star.

Encyclopedic Entry: planet

rain

Noun

liquid precipitation.

Encyclopedic Entry: rain

river

Noun

large stream of flowing fresh water.

Encyclopedic Entry: river

snow

Noun

precipitation made of ice crystals.

vapor

Noun

visible liquid suspended in the air, such as fog.

water cycle

Noun

movement of water between atmosphere, land, and ocean.

Encyclopedic Entry: water cycle

well

Noun

a hole drilled in the Earth to obtain a liquid or gaseous substance.

Credits

Media Credits

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Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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