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.

Two large warm water eddies are swirling to the north of the <a href="/earth/Water/gulf_stream.html&dev=1/earth/Atmosphere/moons/image_linking.html">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&dev=1/earth/Atmosphere/moons/image_linking.html">oceans</a> are full of <a href="/earth/Life/life1.html&dev=1/earth/Atmosphere/moons/image_linking.html">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&dev=1/earth/Atmosphere/moons/image_linking.html">coral reef</a> areas. They occur in all tropical <a href="/earth/Water/ocean.html&dev=1/earth/Atmosphere/moons/image_linking.html">oceans</a> and seas of the world, and feed mainly on <a href="/earth/Life/plankton.html&dev=1/earth/Atmosphere/moons/image_linking.html">zooplankton</a>.<p><small><em>Image courtesy of Corel Photography</em></small></p>The <a href="/earth/Water/circulation1.html&dev=1/earth/Atmosphere/moons/image_linking.html">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&dev=1/earth/Atmosphere/moons/image_linking.html">temperature</a> and <a href="/earth/Water/salinity.html&dev=1/earth/Atmosphere/moons/image_linking.html">salinity</a> that change the <a href="/earth/Water/density.html&dev=1/earth/Atmosphere/moons/image_linking.html">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&dev=1/earth/Atmosphere/moons/image_linking.html">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&dev=1/earth/Atmosphere/moons/image_linking.html">extreme environment</a>, certain species of <a href="/earth/Life/archaea.html&dev=1/earth/Atmosphere/moons/image_linking.html">Archaea</a> and <a href="/earth/Life/classification_eubacteria.html&dev=1/earth/Atmosphere/moons/image_linking.html">Eubacteria</a> thrive, enabling a unique <a href="/earth/Water/life_deep.html&dev=1/earth/Atmosphere/moons/image_linking.html">food chain</a> including fish, shrimp, giant tubeworms, mussels, crabs, and clams.<p><small><em> Courtesy of NASA</em></small></p>A new study has found that <a href="/earth/Atmosphere/airpollution_intro.html&dev=1/earth/Atmosphere/moons/image_linking.html">pollution</a> from <a href="/earth/Atmosphere/particulates.html&dev=1/earth/Atmosphere/moons/image_linking.html">fine particles</a> in the air - mainly the result of burning coal or <a href="/earth/interior/eruptions.html&dev=1/earth/Atmosphere/moons/image_linking.html">volcanic eruptions</a> - can shade <a href="/earth/Life/cnidarian.html&dev=1/earth/Atmosphere/moons/image_linking.html">corals</a> from sunlight and cool the surrounding water resulting in reduced growth rates. Coral growth rates in the Caribbean were affected by volcanic aerosol emissions in the early 20th century and by aerosol emissions caused by humans in the later 20th century. For more information, see the <a href="http://www.exeter.ac.uk/news/featurednews/title_278202_en.html">press release</a>.<p><small><em>Image courtesy of Toby Hudson (Wikimedia Commons)</em></small></p>This first global map of <a href="http://www.windows2universe.org/earth/Water/ocean.html">ocean</a> surface saltiness, released in September 2012 by the NASA Aquarius mission team, shows the distribution of salt in the first 2 cm of the Earth's ocean. <a href="http://www.windows2universe.org/earth/Water/salinity.html">Salinity</a> variations are one of the main drivers of <a href="http://www.windows2universe.org/earth/Water/circulation1.html">ocean circulation</a>, and are closely connected with the <a href="http://www.windows2universe.org/earth/Water/water_cycle.html">cycling of freshwater</a> around the planet. High salinity is seen in the Mediterranean, Atlantic, and the Arabian Sea.<p><small><em>Image courtesy of NASA/GSFC/JPL-Caltech</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

Historical Events

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Did you know?

Did you know that the footprints left on the Moon’s surface by astronauts will last for centuries, because there is no wind on the Moon?

Did you know that the Earth’s magnetic field has reversed its orientation irregularly many times over Earth’s history?

 

Earth and Space Science Concept of the Day

Do you know what this word or phrase means?

Orographic lift
xOrographic lift : Occurs when an air mass is forced to rise over geographic relief from a lower elevation. As the air mass rises it expands and cools adiabatically, which can raise the relative humidity to 100%, create clouds and precipitation.

Click on the word to find out!

Research Highlights

Oldest Earth Mantle Reservoir Discovered

Researchers have found a primitive Earth mantle reservoir on Baffin Island in the Canadian Arctic. Geologist Matthew Jackson and his colleagues from a multi-institution collaboration report the finding--the...Read more


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