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Regions of the Atmosphere

The Earth's atmosphere has layers, which are actually characterized by how the temperature of the atmosphere changes with altitude.


Regions of the Atmosphere Skematic
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The troposphere begins at the Earth's surface, which acts as a source of heat resulting from absorption of visible sunlight. The temperature decreases with height in the troposphere, and so the air is well mixed in this region (Greek: tropos a turning). Weather phenomena such as thunderstorms and clouds occur in this layer, as does most of the commercial airline traffic at present (exceptions include the higher-flying supersonic aircraft, for example, the Concorde). About 6 to 10 miles (10 to 17 kilometers) above the Earth, a new region called the stratosphere begins. The stratosphere is heated from above (absorption of solar ultraviolet radiation by oxygen and ozone) and temperature increases with altitude. In this region there is much slower mixing (Latin: stratum, layer). The "ozone layer" resides in the stratosphere. At about 30 miles (50 kilometers), temperature begins to decrease with altitude again and the mesosphere begins.

Both the stratosphere and the troposphere have important direct and indirect effects on the well-being of humankind. In this century, it has become increasingly clear that humans are influencing the chemical composition of the troposphere and stratosphere in ways that can impact conditions at the Earth's surface. Some of the most challenging environmental issues of our time have arisen, and thus the need for ozone research and monitoring has become very important.

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