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With Explore the Planets, investigate the planets, their moons, and understand the processes that shape them. By G. Jeffrey Taylor, Ph.D. See our DVD collection.

Earth's Atmosphere

The atmosphere is a mixture of nitrogen (78%), oxygen (21%), and other gases (1%) that surrounds Earth. High above the planet, the atmosphere becomes thinner until it gradually reaches space. It is divided into five layers. Most of the weather and clouds are found in the first layer.

The atmosphere is an important part of what makes Earth livable. It blocks some of the Sun's dangerous rays from reaching Earth. It traps heat, making Earth a comfortable temperature. And the oxygen within our atmosphere is essential for life.

Over the past century, greenhouse gases and other air pollutants released into the atmosphere have been causing big changes like global warming, ozone holes, and acid rain.

<a
  href="/earth/Atmosphere/tstorm/tstorm_lightning.html&edu=elem&dev=1">Lightning</a>
  is the most spectacular element of a <a
  href="/earth/Atmosphere/tstorm.html&edu=elem&dev=1">thunderstorm</a>.
  A single stroke of lightning can <a
  href="/earth/Atmosphere/temperature.html&edu=elem&dev=1">heat</a>
  the air around it to 30,000 degrees Celsius (54,000 degrees Fahrenheit)! This
  extreme heating causes the air to expand explosively. The expansion creates a
  shock wave that turns into a booming <a
  href="/earth/Atmosphere/tstorm/lightning_thunder.html&edu=elem&dev=1">sound
  wave</a>, better known as thunder.<p><small><em> Image Courtesy of University Corporation for Atmospheric Research/Carlye Calvin</em></small></p><a
  href="/earth/Atmosphere/clouds/stratocumulus.html&edu=elem&dev=1">Stratocumulus
  clouds</a> belong to the <a
  href="/earth/Atmosphere/clouds/low_cloud.html&edu=elem&dev=1">Low
  Cloud</a> (surface-2000m) group. These clouds are low, lumpy, and gray.  Only light <a
  href="/earth/Atmosphere/precipitation.html&edu=elem&dev=1">precipitation</a>,
  generally in the form of <a
  href="/earth/Atmosphere/precipitation/drizzle.html&edu=elem&dev=1">drizzle</a>,
  occurs with stratocumulus clouds. To distinguish between a stratocumulus and
  an <a
  href="/earth/Atmosphere/clouds/altocumulus.html&edu=elem&dev=1">altocumulus</a>
  cloud, point your hand toward the cloud. If the cloud is about the size of
  your fist, then it is stratocumulus.<p><small><em>            Courtesy of Carlye Calvin/UCAR</em></small></p>How did life evolve on <a href="/earth/earth.html&edu=elem&dev=1">Earth</a> during the <a href="/earth/past/Archean.html&edu=elem&dev=1">Archean</a>, when the <a href="/sun/sun.html&edu=elem&dev=1">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&edu=elem&dev=1">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&edu=elem&dev=1">greenhouse</a> gas concentration was the same as today.  <a href="http://www.manchester.ac.uk/aboutus/news/display/?id=10798">Researchers</a> studying the <a href="/physical_science/physics/atom_particle/isotope.html&edu=elem&dev=1">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&edu=elem&dev=1">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&edu=elem&dev=1">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&edu=elem&dev=1">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=elem&dev=1">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</em></small></p>Does Earth science matter?  The power outage experienced by residents in New York City on 10/30/2012 due to Hurricane Sandy demonstrates the interconnectedness of our society, and the power of the Earth system.  Every person should have an understanding of how the Earth system works so they can live better lives, protect those they love, and make wise choices.  Earth science education is critical!<p><small><em>Image courtesy of Hybirdd, licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.</em></small></p>An image of Hurricane Sandy taken by the GOES-13 satellite on October 28.  This category 1 <a href="/earth/Atmosphere/hurricane/hurricane.html&edu=elem&dev=1">hurricane</a> was huge, spanning a horizontal distance of about one-third the US continental landmass.  The storm came onshore in New Jersey, and gradually moved northeast.  The storm disrupted the lives of tens of millions in the eastern US, doing billions of dollars in damage, resulting in over 30 deaths.  Visit the National Hurricane Center's webpage on <a href="http://www.nhc.noaa.gov/">Hurricane Sandy</a> for details.<p><small><em>Image courtesy of NASA</em></small></p><a
  href="/earth/Atmosphere/clouds/lenticular.html&edu=elem&dev=1">Lenticular
  clouds</a> form on the downwind side of mountains. <a
  href="/earth/Atmosphere/wind.html&edu=elem&dev=1">Wind</a>
  blows most types of clouds across the sky, but lenticular clouds seem to stay
  in one place. Air moves up and over a mountain, and at the point where the
  air goes past the mountaintop the lenticular cloud forms, and then the air <a
  href="/earth/Water/evaporation.html&edu=elem&dev=1">evaporates</a>
  on the side farther away from the mountains.  This close up of lenticular
  clouds was taken at sunset on November 20, 2006 in Boulder, Colorado.<p><small><em>       Courtesy of Roberta Johnson</em></small></p>

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA