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/clouds/stratocumulus.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">Stratocumulus
  clouds</a> belong to the <a
  href="/earth/Atmosphere/clouds/low_cloud.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">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/earth/Atmosphere/moons/triton_atmosphere.html">precipitation</a>,
  generally in the form of <a
  href="/earth/Atmosphere/precipitation/drizzle.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">drizzle</a>,
  occurs with stratocumulus clouds. To distinguish between a stratocumulus and
  an <a
  href="/earth/Atmosphere/clouds/altocumulus.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">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>On November 7, 2013, Typhoon Haiyan (Yolanda in the Philippines) made landfall, with imated wind speeds of ~315 km/hr - the strongest <a href="/earth/Atmosphere/hurricane/intensity.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">tropical cyclone</a> to make landfall in recorded history.  As Haiyan moved across the Philippines before reaching Vietnam and China, its <a href="/earth/Atmosphere/wind.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">winds</a> and <a href="/earth/Atmosphere/hurricane/surge.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">storm surge</a> left devastation in its wake, leading to massive loss of life, destruction of homes, and hundreds of thousands of displaced inhabitants. <a href="http://www.cnn.com/2013/11/09/world/iyw-how-to-help-typhoon-haiyan/index.html">How to Help</a><p><small><em>Image courtesy of COMS-1, SSEC, University of Wisconsin-Madison</em></small></p><a
  href="/earth/Atmosphere/clouds/lenticular.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">Lenticular
  clouds</a> form on the downwind side of mountains. <a
  href="/earth/Atmosphere/wind.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">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/earth/Atmosphere/moons/triton_atmosphere.html">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>On May 20, 2013, a massive EF5 <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> hit Moore, Oklahoma, devastating communities and lives.  The tornado, on the ground for 40 minutes, took a path through a subdivision of homes, destroying block after block of homes, and hitting two elementary schools just as school was ending as well as a hospital. Hundreds of people were injured, and 24 were killed.<p><small><em>Image courtesy of Ks0stm, Creative Commons Attribution-Share Alike 3.0 Unported license</em></small></p>How did life evolve on <a href="/earth/earth.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">Earth</a> during the <a href="/earth/past/Archean.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">Archean</a>, when the <a href="/sun/sun.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">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/earth/Atmosphere/moons/triton_atmosphere.html">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=elem&dev=1/earth/Atmosphere/moons/triton_atmosphere.html">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>

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