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 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.
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 ...
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Argonne advanced battery research driving to displace gasoline (w/ Video)
Dec 21, 2009 |
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(PhysOrg.com) -- In excess of seven million barrels of gasoline are consumed by vehicles in the United States every day. As scientists race to find environmentally sound solutions to fuel the world’s ever-growing ...
Japanese researcher unveils 'hummingbird robot'
11 hours ago |
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Japanese researchers said Monday they had developed a "hummingbird robot" that can flutter around freely in mid-air with rapid wing movements.
'Particle soup' discovery will improve climate predictions
Space & Earth / Earth Sciences
Dec 21, 2009 |
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(PhysOrg.com) -- New research from scientists at The University of Manchester is set to improve predictions about climate and air quality - and make life easier for those suffering from respiratory problems.
NASA Tests Unique Jumbo Jet with Opening in Side; Plane's Airborne Telescope Will Be Used to Study Cosmos
Space & Earth / Space Exploration
Dec 21, 2009 |
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(PhysOrg.com) -- A NASA jumbo jet that will help scientists unlock the origins of the universe with infrared observations reached a milestone Friday when doors covering the plane's telescope were fully opened ...
Naturally occurring lipid blocks RSV infection in lungs
Dec 21, 2009 |
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Researchers at National Jewish Health have discovered that a naturally occurring lipid in the lung can prevent RSV infection and inhibit spread of the virus after an infection is established. RSV is the major cause of hospitalization ...
New materials designed to deal with hypersonic and supersonic hot stuff (w/ Video)
Dec 24, 2009 |
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University of Queensland researchers are testing new materials to withstand the extreme heat experienced by hypersonic vehicles in flight so they can fly for substantially longer.
As shuttle's career nears an end, NASA turns focus to satellites
Space & Earth / Space Exploration
Dec 26, 2009 |
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NASA heads into 2010 with the bittersweet assignment of retiring the space shuttle after nearly three decades. But that's not all the agency has planned: There are also launches of three new satellites aimed at better understanding ...
Cornellians build computer climate-change model
Space & Earth / Earth Sciences
Dec 21, 2009 |
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(PhysOrg.com) -- Researchers are contributing to a new model of climate change that may give more accurate predictions of the amount of carbon dioxide and other greenhouse gases in Earth's future.
Panasonic develops direct methanol fuel cell system with high power output and durability
Dec 26, 2009 |
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Panasonic Corporation announced it has developed a direct methanol fuel cell system which can produce an average power output of 20 W by increasing the output per cubic centimeter twice that of its previous prototype. Using ...
Imaging tests identify role of allergies in chronic sinus disease
Dec 21, 2009 |
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Exposing patients with chronic sinus disease to allergens and then obtaining repeated images by X-ray or ultrasound reveals that nasal allergies may be involved in some cases of chronic sinus disease, according to a report ...
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