Earth's Atmosphere Essay

1627 Words Nov 21st, 2012 7 Pages
Earth's atmosphere is a unique reservoir of gases, the product of nearly 5 billion years of development. It sustains us and protects us from hostile radiation and particles from the Sun and beyond-the atmosphere serves as an efficient filter.When astronauts work in space, they must wear a bulky spacesuit that does everything to sustain and protect them that the atmosphere does for us all the time.Atmosphere is a gaseous mixture of ancient origin, the sum of all the exhalations and inhalations of life on Earth throughout time.
The principal substance of this atmosphere is air, the medium of life as well as a major industrial and chemical raw material. Air is a simple mixture of gases that is naturally odorless, colorless,
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The weight (force over a unit area) of the atmosphere, or air pressure, pushes in on all of us.Fortunately, that same pressure also exists inside us pushing outward; otherwise we would be crushed by the mass of air around us.Gravity compresses air, making it denser near Earth's surface; it thins rapidly with increasing altitude.
Atmospheric Composition Criterion
1.Using chemical composition as a criterion, the atmosphere divides into two broad regions, the heterosphere (80 to 480 km altitude) and the homosphere (Earth's surface to 80 km altitude). As you read, note that we follow the same path that incoming solar radiation travels through the atmosphere to Earth's surface.
2.The heterosphere is the outer atmosphere in terms of composition. It begins at about 80 km (50 mi) altitude and extends outward to the transition to the exosphere and interplanetary space.The International Space Station and most Space Shuttle missions orbit in the upper heterosphere.As the prefix hetero - implies, this region is not unifom - its gases are not evenly mixed.
3.This distribution is quite different from the nicely blended gases we breathe near Earth's surface, in the homosphere. Gases in the heterosphere occur in distinct layers sorted by gravity according to their atomic weight, with the lightest elements (hydrogen and helium) at the margins of outer space and the heavier elements (oxygen and nitrogen) dominant in the lower heterosphere.
4.Below the

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