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
Air Force grant to tighten online encryption
Technology / Computer Sciences
17 hours ago |
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(PhysOrg.com) -- Computer scientist Rafael Pass is seeking new approaches to cryptographic security with a $600,000, five-year grant from the Air Force Office of Scientific Research.
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A unique geography -- and soot and dust -- conspire against Himalayan glaciers
Space & Earth / Earth Sciences
5 hours ago |
3 / 5 (1) |
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"So many disparate elements, both natural and man-made, converge in the Himalayas," said William Lau, a climatologist from NASA's Goddard Space Flight Center in Greenbelt, Md. "There's no other place in the ...
Portions of Arctic coastline eroding, no end in sight, says new study
Space & Earth / Earth Sciences
16 hours ago |
3.9 / 5 (7) |
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The northern coastline of Alaska midway between Point Barrow and Prudhoe Bay is eroding by up to one-third the length of a football field annually because of a "triple whammy" of declining sea ice, warming ...
New Study Turns Up the Heat on Soot's Role in Himalayan Warming (w/ Video)
Space & Earth / Earth Sciences
18 hours ago |
5 / 5 (1) |
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(PhysOrg.com) -- Soot from fire in an unventilated fireplace wafts into a home and settles on the surfaces of floors and furniture. But with a quick fix to the chimney flue and some dusting, it bears no impact ...
AOptix Technologies and NuCrypt demonstrate physical-layer quantum encryption
22 hours ago |
4.7 / 5 (3) |
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AOptix Technologies, a leading edge developer of ultra-high bandwidth laser communication solutions, and NuCrypt, a provider of technology for ultra-high security over optical communication networks, disclosed today the recent ...
Low-cost temperature sensors, tennis balls to monitor mountain snowpack
Dec 14, 2009 |
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(PhysOrg.com) -- Fictional secret agent Angus MacGyver knew that tough situations demand ingenuity. Jessica Lundquist takes a similar approach to studying snowfall. The University of Washington assistant professor ...
Study unveils potential genetic links to lung disease risk
Dec 14, 2009 |
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A new study involving data from more than 20,000 individuals has uncovered several DNA sequences linked to impaired pulmonary function. The research, an analysis that combined the results of several smaller studies, provides ...
Ethanol-powered vehicles generate more ozone than gas-powered ones
Dec 14, 2009 |
4.3 / 5 (7) |
4
Ethanol, often promoted as a clean-burning, renewable fuel that could help wean the nation from oil, would likely worsen health problems caused by ozone, compared with gasoline, especially in winter, according to a new study ...
WISE satellite blasts off on space-map mission
Space & Earth / Space Exploration
Dec 14, 2009 |
4.8 / 5 (6) |
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NASA launched Monday a new breed of satellite called WISE on a mission to orbit Earth and map the skies to find elusive cosmic objects, including potentially dangerous asteroids.
Anti-gravity treadmill: Therapy that's like a walk on the moon
Dec 14, 2009 |
5 / 5 (3) |
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A treadmill developed at NASA Ames Research Center more than a decade ago for exercising in space has seen more athletes than astronauts lately.
Hi-tech, eco-friendly dream home takes shape in Japan
Dec 14, 2009 |
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On Tokyo Bay, at the edge of the largest urban sprawl on Earth, sits what may be an environmentalist's dream home.
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