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The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
Nitrogen (N2) is the most abundant gas in Earth's atmosphere, including the troposphere. This cartoon also depicts several other tropospheric gases, including oxygen (O2), carbon dioxide (CO2), water vapor (H2O), methane (CH4), sulfur dioxide (SO2), and carbon monoxide (CO).
Click on image for full size
Image courtesy UCAR, modified by Windows to the Universe staff (Randy Russell).

Chemical Composition of Earth's Atmosphere

Earth's atmosphere consists of about 78% nitrogen, 20% oxygen, and a mixture of small amounts of numerous other ingredients. Some of the minor constituents do, however, have big impacts. For example, greenhouse gases such as carbon dioxide and methane exert a large influence on the temperature of our planet.

The chemical composition of air varies across the different layers of Earth's atmosphere.

The oceans and the biosphere exchange vast quantities of gases with the atmosphere's lowest layer. The Carbon and Nitrogen Cycles play key roles in these processes.

The activities of humans play an increasingly important role in atmospheric chemistry. Fossil fuel burning generates sulfur oxides, which create sulfuric acid - a component of acid rain. Exhaust gases from cars and trucks produce nitrogen oxides, which contribute to the formation of smog and of nitric acid - another component of acid rain.

Last modified July 13, 2009 by Randy Russell.

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Cool It! Game

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Nitrogen

Nitrogen is a chemical element with an atomic number of 7 (it has seven protons in its nucleus). Molecular nitrogen (N2) is a very common chemical compound in which two nitrogen atoms are tightly bound...more

Oxygen

Oxygen is a chemical element with an atomic number of 8 (it has eight protons in its nucleus). Oxygen forms a chemical compound (O2) of two atoms which is a colorless gas at normal temperatures and pressures....more

Earth's Greenhouse Gases

Less than 1% of the gases in Earth's atmosphere are called greenhouse gases. Even though they are not very abundant, these greenhouse gases have a major effect. Carbon dioxide (CO2), water vapor (H2O),...more

Carbon Dioxide - CO2

Carbon dioxide is a colorless and non-flammable gas at normal temperature and pressure. Although much less abundant than nitrogen and oxygen in Earth's atmosphere, carbon dioxide is an important constituent...more

Methane - CH4

Methane is gas that is found in small quantities in Earth's atmosphere. Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. Methane is a powerful greenhouse gas....more

Atmospheric Chemistry

Chemistry plays an influential role in the behavior of Earth's atmosphere. The various gases in the atmosphere are constantly mixing with and reacting with each other. Gases released by the oceans, emitted...more

Air Pollution Sources

Air pollution comes from many different sources. Natural processes that affect air quality include volcanic activity, which produce sulfur, chlorine, and ash particulates, and wildfires, which produce...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF