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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.

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/mammatus.html&dev=1">Mammatus
  clouds</a> are pouches of clouds that hang underneath the base of a cloud.
  They are usually seen with <a
  href="/earth/Atmosphere/clouds/cumulonimbus.html&dev=1">cumulonimbus
  clouds</a> that produce very <a
  href="/earth/Atmosphere/tstorm.html&dev=1">strong
  storms</a>. This photograph of mammatus clouds was taken on June 21, 2006 in
  Boulder, Colorado, at sunset. Notice how the light from the sun highlights
  the round features of these clouds.<p><small><em>       Courtesy of Roberta Johnson</em></small></p><a href="/earth/Atmosphere/NLC.html&dev=1">Noctilucent</a>
  clouds are the highest clouds in the sky, but they are not associated with
  weather like the <a
  href="/earth/Atmosphere/clouds/cloud_types.html&dev=1">other
  clouds</a> we regularly see in the sky.  Noctilucent clouds form very high in
  the <a href="/earth/Atmosphere/overview.html&dev=1">atmosphere</a>,
  in the <a
  href="/earth/Atmosphere/mesosphere.html&dev=1">mesosphere</a>. 
  They are best seen from Earth at sunset. This image was taken on June 15,
  2007, in Budapest, Hungary.  Normally seen from locations near the <a
  href="/earth/polar/polar.html&dev=1">poles</a> of
  the Earth, in recent years they have also been seen at much lower-latitude
  locations.<p><small><em> Image Courtesy of NASA/Veres Viktor</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&dev=1">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&dev=1">winds</a> and <a href="/earth/Atmosphere/hurricane/surge.html&dev=1">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&dev=1">Lenticular
  clouds</a> form on the downwind side of mountains. <a
  href="/earth/Atmosphere/wind.html&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&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>How did life evolve on <a href="/earth/earth.html&dev=1">Earth</a> during the <a href="/earth/past/Archean.html&dev=1">Archean</a>, when the <a href="/sun/sun.html&dev=1">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&dev=1">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&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&dev=1">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&dev=1">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&dev=1">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&dev=1">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&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>

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