Current Events

  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
  • Massive Tornado Outbreak on Tornado Alley
    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Io...Read more

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    Massive Tornado Outbreak on Tornado Alley

    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Iowa, Illinois and Missouri. On May 20th, a massive tornado struck Moore, Oklahoma, devastating communities - destroying over 100 homes and hitting two elementary schools and a hospital - with many casualties and deaths. Our thoughts are with our friends and colleagues suffering from these storms. For more on the May 20th storms, see the NOAA Storm Prediction Center Storm Report.
  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.

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.

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><a href="/earth/Atmosphere/clouds/mammatus.html">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">cumulonimbus clouds</a> that produce very <a href="/earth/Atmosphere/tstorm.html">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/clouds/lenticular.html">Lenticular clouds</a> form on the downwind side of mountains. <a href="/earth/Atmosphere/wind.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">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><a href="/earth/Atmosphere/NLC.html">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">other clouds</a> we regularly see in the sky.  Noctilucent clouds form very high in the <a href="/earth/Atmosphere/overview.html">atmosphere</a>, in the <a href="/earth/Atmosphere/mesosphere.html">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">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><a href="/earth/Atmosphere/clouds/stratocumulus.html">Stratocumulus clouds</a> belong to the <a href="/earth/Atmosphere/clouds/low_cloud.html">Low Cloud</a> (surface-2000m) group. These clouds are low, lumpy, and gray. Only light <a href="/earth/Atmosphere/precipitation.html">precipitation</a>, generally in the form of <a href="/earth/Atmosphere/precipitation/drizzle.html">drizzle</a>, occurs with stratocumulus clouds. To distinguish between a stratocumulus and an <a href="/earth/Atmosphere/clouds/altocumulus.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>Anti-crepuscular rays are beams of sunlight that appear to converge on a point opposite the sun. They are similar to crepuscular rays, but are seen opposite the sun in the sky. Anti-crepuscular rays are most frequently visible near sunrise or sunset. This photo of anti-crepuscular rays was taken at sunset in Boulder, Colorado. Crepuscular rays are usually much brighter than anti-crepuscular rays.<p><small><em> Image Courtesy of Carlye Calvin</em></small></p>

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Explore Earth's Atmosphere

Layers of the Atmosphere

The atmosphere is divided into five layers. It is thickest near the surface and thins out with ...Read more

Weather

Weather is the state of the atmosphere at a given time and place. Most weather takes place ...Read more

Climate

Warm near the equator and cold at the poles, our planet is able to support a variety of living ...Read more

The Polar Atmosphere

Phenomena in the Polar Atmosphere There are some unique phenomena that happen in the atmosphere ...Read more

Atmospheric Optics

Have you ever seen clouds in the sky that looked different than "normal" clouds? Or have you ...Read more

Air Pollution

What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have ...Read more

Ozone Holes

The Ozone Hole is a major "thinning" of the ozone layer in Earth's atmosphere. It ...Read more

Modeling the Atmosphere

Clouds are an important part of Earth's weather and climate. Scientists use computer models ...Read more

Arts and Culture About Clouds, Weather, and Climate

Whether it is how an artist paints the shapes of clouds or how a poet describes a gloomy weather ...Read more

Atmosphere News

Read about current science, happenings and discoveries related to Earth's atmosphere! ...Read more

More about Earth's Atmosphere

Historical Events

5/30 7.5 magnitude quake hits Quetta, Pakistan in 1935
5/31 7.9 magnitude earthquake hits Peru in 1970
6/8 Giovanni Cassini, an Italian-French astronomer, was born on this date in 1625 Details

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Did you know that you can now share your poems about our collection of cloud art photos. Have fun!

Do you know what happened during the “Little Ice Age”?

 

Earth and Space Science Concept of the Day

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Moho
xMoho : The boundary between the crust and the mantle in the earth. This is a depth where seismic waves change velocity and there is also a change in chemical composition. Also termed the Mohorovicic' discontinuity after the Croatian seismologist Andrija Moh

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Research Highlights

Even in the Desert, Plants Feel the Heat of Global Warming

Global warming is a hot topic, and it's causing concern for scientists studying winter annuals in the Sonoran Desert. While desert winters have become warmer and drier over the years, climate changes have...Read more

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