Earth's atmosphere
hideThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. It has a mass of about five quadrillion metric tons. Dry air contains roughly (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and trace amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.
There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. An altitude of 120 km (75 mi) marks the boundary where atmospheric effects become noticeable during atmospheric reentry. The Kármán line, at 100 km (62 mi), is also frequently regarded as the boundary between atmosphere and outer space. Three quarters of the atmosphere's mass is within 11 km (6.8 mi; 36,000 ft) of the surface.
For more information about Earth's atmosphere, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with air
New climate targets may not change daily life much
Nov 27, 2009 |
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(AP) -- Americans' day-to-day lives won't change noticeably if President Barack Obama achieves his newly announced goal of slashing carbon dioxide pollution by one-sixth in the next decade, experts say.
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Gift Guide: Accessories to jazz up mobile phones
Electronics / Consumer & Gadgets
Nov 27, 2009 |
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People you know have spent small fortunes on shiny new smart phones such as the iPhone 3GS, a BlackBerry or the Droid. But the devices still don't have all the features they want.
China to launch second lunar probe: state media
Space & Earth / Space Exploration
Nov 27, 2009 |
5 / 5 (5) |
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China will launch its second moon orbiter next October, state media reported Friday, as it powers ahead with a space programme that has sparked concerns abroad.
Fujitsu Develops Technology for Low-Temperature Full-Service Direct Formation of Graphene Transistors on Large-Scale Sub
Nov 27, 2009 |
5 / 5 (17) |
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Fujitsu Laboratories today announced, as a world first, the development of a novel technology for forming graphene transistors directly on the entire surface of large-scale insulating substrates at low temperatures ...
Tough yet stiff deer antler is materials scientist's dream
Nov 27, 2009 |
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Prized for their impressive antlers, red deer have been caught in the hunters' sights for generations. But a deer's antlers are much more than decorative. They are lethal weapons that stags crash together when duelling. John ...
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