News tagged with air

Related topics: air pollution · air quality · pollution

Federal report shows drop in preterm birth rate

The number of American infants born before the 37th week of pregnancy dropped slightly in 2013, as did the percentage of children with asthma under the age of 17. The percentage of teens who experienced a major depressive ...

Jul 10, 2015
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Advice for older people on staying safe in hot weather

Summer weather can pose special health risks to older adults and people with chronic medical conditions. It is critically important that adults particularly susceptible to hyperthermia and other heat-related illnesses know ...

Jul 08, 2015
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Earth's atmosphere

The 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.

This text uses material from Wikipedia, licensed under CC BY-SA

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