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
States call on EPA for tougher air pollution regulations
Nov 06, 2009 |
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Twelve states and the District of Columbia urged the Environmental Protection Agency Thursday to adopt more rigorous national policies so they can meet federal air pollution reduction requirements for the region.
Air pollution increases infants' risk of bronchiolitis
Nov 06, 2009 |
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Infants who are exposed to higher levels of air pollution are at increased risk for bronchiolitis, according to a new study.
Ford to put air bags into back seat belts of SUV (w/ Video)
Nov 05, 2009 |
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(AP) -- Air bags have long been mounted in the steering wheel, dashboard and sides of vehicles. Now, they're in the seat belts. Ford Motor Co. plans to introduce seat belt-mounted air bags in the back seat ...
Nocturnal wind maximum mapped for first time
Space & Earth / Earth Sciences
Nov 05, 2009 |
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On beautiful, sunny days with quiet weather conditions a strong wind develops in the evening at a height of about 200 metres.
Study finds big air pollution impacts on local communities
Nov 04, 2009 |
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Heavy traffic corridors in the cities of Long Beach and Riverside are responsible for a significant proportion of preventable childhood asthma, and the true impact of air pollution and ship emissions on the disease has likely ...
Common plants can eliminate indoor air pollutants
Nov 04, 2009 |
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Air quality in homes, offices, and other indoor spaces is becoming a major health concern, particularly in developed countries where people often spend more than 90% of their time indoors. Surprisingly, indoor ...
Tiny Music Player Made from Wire Bridge (w/ Video)
Nov 04, 2009 |
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(PhysOrg.com) -- In 2008, scientists built a loudspeaker made of carbon nanotubes that produced sound and music based on the thermoacoustic effect. Now, a different team of scientists has built a loudspeaker ...
Car That Runs on Compressed Air Questioned by Critics (w/ Video)
Nov 03, 2009 |
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(PhysOrg.com) -- As electric cars begin breaking into the short-distance vehicle market, one French company thinks that it has an alternative to the electric vehicle: a car that runs on compressed air. Motor ...
Lawmakers seek ban on laptops in airliner cockpits
Nov 03, 2009 |
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(AP) -- Lawmakers are moving to ban the use of computer laptops and other personal electronic devices in airline cockpits to prevent another incident like the Northwest Airlines plane that overshot Minneapolis by 150 miles.
The 'e-Nose': Scientists try to develop an electronic sniffer
Chemistry / Analytical Chemistry
Nov 02, 2009 |
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Sniff, sniff, sniff -- Yum! Sniff, sniff, sniff -- Oh, yuck!!! For almost 25 years, chemists and other scientists have tried to build a machine that can do exactly that.
Researchers discover links between city walkability and air pollution exposure
Nov 02, 2009 |
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A new study compares neighborhoods' walkability (degree of ease for walking) with local levels of air pollution and finds that some neighborhoods might be good for walking, but have poor air quality. Researchers involved ...
Flying MAV Navigates Without GPS (w/ Video)
Nov 02, 2009 |
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(PhysOrg.com) -- During the last several years, researchers have been building micro air vehicles (MAVs) that can autonomously fly through different environments by relying on GPS for navigation. Recently, ...
Flying with the flu: Expert panel revisits the danger of air travel during a pandemic
Oct 29, 2009 |
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Attempting to ground planes during pandemics may not be worth the trouble, a panel of experts from the government, academia and the airlines industry heard at a recent meeting in Washington.
New rechargeable zinc-air batteries coming soon
Oct 29, 2009 |
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(PhysOrg.com) -- A new breed of rechargeable zinc-air batteries is soon to be available, and may replace lithium-ion batteries in cell phones, laptops and other consumer items. Lithium-ion batteries store ...
Robot Armada Might Scale New Worlds
Space & Earth / Space Exploration
Oct 28, 2009 |
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(PhysOrg.com) -- An armada of robots may one day fly above the mountain tops of Saturn's moon Titan, cross its vast dunes and sail in its liquid lakes.
