Water

Water is found in many places on Earth including on the surface of the planet, within rocks below the surface, and in the atmosphere.  Water travels between different areas of the Earth through the water cycle. About 70% of the Earth surface is covered with water, and most of that is the ocean. Only a small portion of the Earth's water is freshwater, which is found in rivers, lakes, and groundwater. Freshwater is needed for drinking, farming, and washing. In addition to liquid water, water is also present on Earth in the form of ice. Without water, life as we know it would not exist.

This beautiful sunset was captured off the coast of Chile in October, 2009. Earth's ocean covers more than 70% of our planet's surface. <a href="/earth/Water/ocean_motion.html&edu=high">Ocean water is always moving</a>. It moves around by <a href="/earth/Water/ocean_currents.html&edu=high">surface ocean currents</a>, <a href="/earth/Water/ocean_upwelling.html&edu=high">upwelling</a>, <a href="/earth/Water/ocean_tides.html&edu=high">tides</a>, and the <a href="/earth/Water/circulation1.html&edu=high">global ocean conveyor</a> or <a href="/earth/Water/circulation1.html&edu=high">thermohaline circulation</a>. The ocean's tides are one type of tide created by <a href="/glossary/tidal_forces.html&edu=high">gravitational force</a>.<p><small><em>Image courtesy of Carlye Calvin</em></small></p>Two large warm water eddies are swirling to the north of the <a href="/earth/Water/gulf_stream.html&edu=high">Gulf Stream current</a> in this satellite image recorded with the AVHRR sensor (Advanced Very High Resolution Radiometer) aboard a NOAA satellite on June 11, 1997. Blue colors indicate cooler water, while yellow and orange colors indicate warmer water.<p><small><em>Courtesy of the Ocean Remote Sensing Group, Johns Hopkins University Applied Physics Laboratory</em></small></p>The <a href="/earth/Water/ocean.html&edu=high">oceans</a> are full of <a href="/earth/Life/life1.html&edu=high">life</a>. Anthias are small, peaceful reef fish, and are a significant fraction of the colorful fishes seen in <a href="/earth/climate/coral_change.html&edu=high">coral reef</a> areas. They occur in all tropical <a href="/earth/Water/ocean.html&edu=high">oceans</a> and seas of the world, and feed mainly on <a href="/earth/Life/plankton.html&edu=high">zooplankton</a>.<p><small><em>Image courtesy of Corel Photography</em></small></p>The <a href="/earth/Water/circulation1.html&edu=high">thermohaline circulation</a>, often referred to as the ocean's "conveyor belt", links major surface and deep water currents in the Atlantic, Indian, Pacific, and Southern Oceans. This pattern is driven by changes in water <a href="/earth/Water/temp.html&edu=high">temperature</a> and <a href="/earth/Water/salinity.html&edu=high">salinity</a> that change the <a href="/earth/Water/density.html&edu=high">density</a> of seawater.<p><small><em> Image courtesy <a href="http://www.clivar.org/publications/other_pubs/clivar_transp/d3_transp.htm">CLIVAR</a> (after W. Broecker, modified by E. Maier-Reimer).</em></small></p>Hydrothermal vents in the deep ocean are located at tectonic <a href="/earth/interior/seafloor_spreading.html&edu=high">spreading ridges</a>. While most of the water in the deep ocean is close to freezing, the water at hydrothermal vents is very hot and laden with chemicals. In this <a href="/earth/extreme_environments.html&edu=high">extreme environment</a>, certain species of <a href="/earth/Life/archaea.html&edu=high">Archaea</a> and <a href="/earth/Life/classification_eubacteria.html&edu=high">Eubacteria</a> thrive, enabling a unique <a href="/earth/Water/life_deep.html&edu=high">food chain</a> including fish, shrimp, giant tubeworms, mussels, crabs, and clams.<p><small><em> Courtesy of NASA</em></small></p>The massive 9.0 magnitude <a href="/earth/geology/quake_1.html&edu=high">earthquake</a> off of Honshu, Japan on <a href="/headline_universe/march112011earthquaketsunami.html&edu=high">11 March 2011</a> generated a <a href="/earth/tsunami1.html&edu=high">tsunami</a> that exceeded 10 meters on the coast near the epicenter. This image shows model projections for the tsunami wave height in cm which are in good agreement with the observed waves. Our thoughts and prayers are with those who were lost, and their families, as we remember this event.<p><small><em><a href="http://blogs.agu.org/wildwildscience/files/2011/03/680_20110311-TsunamiWaveHeight.jpg">NOAA Tsunami Wave Height Projections image</a></em></small></p>

Explore Water

The Ocean

Earth's ocean covers more than 70% of our planet's surface. There are five major ocean basins. ...Read more

Rivers and Other Freshwater

Rivers are very important to Earth because they are major forces that shape the landscape. ...Read more

Groundwater

Most of the water we are aware of is in ponds, rivers, oceans, streams, lakes, puddles, and ...Read more

Ice: Frozen Water

The cryosphere includes the parts of the Earth system where water is in its frozen (solid) ...Read more

Our Changing Planet

When we look around us, we can see that our planet's climate is changing rapidly. The National ...Read more

Clouds: Water in the Sky

Clouds can come in all sizes and shapes, and can form near the ground or high in the atmosphere. ...Read more

The Water Cycle

Water is always on the move. Rain falling where you live may have been water in the ocean just ...Read more

Life in the Ocean

The ocean holds the largest of all biomes on Earth. It covers 70% of the planet’s surface. ...Read more

Ocean Chemistry

Earth's oceans are, of course, full of water. That water is not, however, simply pure H2O. ...Read more

Water News

Read about current science, happenings and discoveries related to water on Earth! ...Read more

Water Images

Access wonderful captioned photos and illustrations that will inspire and excite you. ...Read more

More about Water

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Did you know?

Did you know that the Earth’s magnetic field protects us from radiation from space?

Did you know that lunar eclipses are produced by the Earth casting its shadow on the Moon?

 

Earth and Space Science Concept of the Day

Do you know what this word or phrase means?

Chinook
xChinook : A dry down-slope wind which occurs on the downwind side of a mountain range. It is a rain shadow wind which results from the subsequent (adiabatic) warming of air which has dropped most of its moisture on windward slopes.

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Research Highlights

Gulf Oil Spill: Mississippi River Hydrology May Help Reduce Oil Onshore

The Gulf of Mexico: what role will the Mississippi River play in oil washing ashore and into delta wetlands? One of the spill's greatest environmental threats is to Louisiana's wetlands, scientists believe....Read more


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