Energy & Green Tech

Should Uber and Lyft be electrifying more vehicles?

Professor Jeremy Michalek and his Ph.D student Matthew Bruchon have published a study investigating what vehicle electrification would look like in a world where ridesourcing companies like Uber and Lyft were held responsible ...

Robotics

Efforts to deliver the first drone-based, mobile quantum network

Hacked bank and Twitter accounts, malicious power outages and attempts to tamper with medical records threaten the security of the nation's health, money, energy, society and infrastructure. Harnessing the laws of nature—namely ...

Business

United Airlines sees a supersonic future

United Airlines aims to bring back supersonic travel before the decade is over with a plane that is currently just an artist's drawing—even the prototype hasn't flown yet.

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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