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
Scientists discover fog on Titan
Space & Earth / Space Exploration
Dec 18, 2009 |
4.8 / 5 (11) |
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Saturn's largest moon, Titan, looks to be the only place in the solar system—aside from our home planet, Earth—with copious quantities of liquid (largely, liquid methane and ethane) sitting on its surface. ...
Air bags not a risk to pregnant women in motor vehicle crashes, study finds
Dec 22, 2009 |
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(PhysOrg.com) -- A new ground-breaking study from University of Washington researchers has found that air bags do not seem to elevate risk of most potential adverse outcomes during pregnancy.
Scientists study hummingbirds flight to develop self-propelled surveillance devices
Dec 16, 2009 |
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The secret to the flight of the hummingbird and other tiny birds and insects lies in the looping, swirling flow of air, called a vortex, that their flapping wings create.
Pollution linked to hospitalizations for pneumonia in older adults
Dec 23, 2009 |
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Older adults with long-term exposure to higher levels of pollution are at higher risk for hospitalization for pneumonia, according to researchers in Canada.
School classroom air may be more polluted with ultrafine particles than outdoor air
Dec 22, 2009 |
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The air in some school classrooms may contain higher levels of extremely small particles of pollutants — easily inhaled deep into the lungs — than polluted outdoor air, scientists in Australia and Germany ...
Beijing vehicles exceed four million: state media
Dec 19, 2009 |
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The number of registered vehicles in Beijing topped four million this week, state media reported, meaning a quarter of the 16 million permanent residents in China's capital have a car.
New approach to emissions makes climate and air quality models more accurate, major study finds
Space & Earth / Earth Sciences
Dec 10, 2009 |
3.9 / 5 (7) |
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It's no secret that the emissions leaving a car tailpipe or factory smokestack affect climate and air quality. Even trees release chemicals that influence the atmosphere. But until now, scientists have struggled to know where ...
Research shows some plants can remove indoor pollutants
Dec 02, 2009 |
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(PhysOrg.com) -- Some plants have the ability to drastically reduce levels of indoor pollutants, according to new research at the University of Georgia. Researchers showed that certain species can effectively ...
Californians -- and their cell phones -- will help computer scientists monitor air pollution
Technology / Computer Sciences
Dec 04, 2009 |
1 / 5 (2) |
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You want to go for a run, but you don't want to run in polluted air that might aggravate your asthma. University of California, San Diego computer scientists are creating a network of environmental sensors ...
How to spur energy storage innovations
Dec 17, 2009 |
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Imagine flying all the way from coast to coast, completely guilt-free, in an airplane that doesn’t emit a single particle of greenhouse gas or air pollutants. That could happen someday, perhaps brought to ...
Hydrogen-Powered Ion Tiger Sets 26-hour Flight Endurance Record
Nov 30, 2009 |
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The Naval Research Laboratory's Ion Tiger, a hydrogen-powered fuel cell unmanned air vehicle (UAV), has flown 26 hours and 1 minute carrying a 5-pound payload, setting another unofficial flight endurance record ...
Next-Generation Air Transportation System to Ultimately Succeed, Computer Scientist Predicts
Dec 16, 2009 |
5 / 5 (1) |
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(PhysOrg.com) -- The Next Generation Air Transportation System, known as NextGen, is due for national implementation in stages between now and 2018. "I am predicting ultimate success and a system that will provide a much ...
Air Force grant to tighten online encryption
Technology / Computer Sciences
Dec 14, 2009 |
4 / 5 (1) |
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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.
More than 1,000 patients in US admitted annually for aviation-related injuries
Dec 01, 2009 |
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The first ever published study of aviation-related injuries and deaths in the U.S. finds that more than 1,013 patients are admitted to U.S. hospitals with aviation-related injuries annually, and that 753 aviation-deaths occur ...
Rocket launches Air Force satellite from Fla.
Space & Earth / Space Exploration
Dec 06, 2009 |
5 / 5 (1) |
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(AP) -- A rocket carrying an Air Force satellite that will be used by the military has launched from Cape Canaveral.
