Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly 78% nitrogen and 21% oxygen, trace amounts of other gases, and water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.
The atmosphere has no abrupt cut-off. It slowly becomes thinner and fades away into space. There is no definite boundary between the atmosphere and outer space. Three-quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, persons who travel above an altitude of 50.0 miles (80.5 km) are designated as astronauts. An altitude of 120 km (75 mi or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Karman line, at 100 km (62 mi), is also frequently used as the boundary between atmosphere and space.
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AirlinesAndAirportLinks.com - Database of links to airlines and airports around the world.
Meta Description: [ An exhaustive and cross-referenced database of links to airline and airport websites of the world, including three-letter airport codes and two-letter airline codes. ]
Airwise - News and information source for airlines, airports and air travel. Also includes discussion boards.
Meta Description: [ The news and information source for airlines, airports and air travel. Book your next trip online with our flight, hotel and rental car booking service, and check if that flight is on time with flight arrival information for major airlines. ]
Bel Air Travel - Offers Canadian low-fare flight reservations.
FlightArrivals.com - Comprehensive, independent arrival, departure, delay and cancellation information for all commercial flights across the US and Canada.
Meta Description: [ FlightArrivals.com: Real time flight arrivals, flight departures, flight delays and flight cancellations for all commercial airline flights in/out the US. ]
HowStuffWorks: How Airport Security Works - Illustrated tour of the current technology used in airport security.
Meta Description: [ Airport security is one of the biggest concerns for travelers these days. Find out how high-tech solutions are used to make flying as safe as possible ]
IAPA - International Airline Passengers Association - Offers hotel discounts, car rental savings, flight reservations, travel insurance, airport VIP lounge access, airline safety representation and luggage protection.
Meta Description: [ The Travel Services Page for IAPA Members ]
Instone Air Services - A specialist in the air transport of animals worldwide.
ITA Software - Plan air travel with an advanced shopping tool displaying a comprehensive summary of all your flight travel options. Cannot purchase tickets online at this time. North America flights only.
OAG - The Official Airline Guide - Independent provider of travel information products and services, offering business travelers, corporations and the global travel industry information to make effective travel planning decisions.
Meta Description: [ This is the only website you need visit for flight and travel information. Access unique flight and air route tools from the OAG flight schedules database. Find information on over 200 countries and 400 airports as well as directory information on most of the world's scheduled airlines. ]
The Budget Traveller's Guide to Sleeping in Airports - Reviews including the best and worst around the world. Tips for sleeping comfortably and safely while grounded, articles, news and other strange places to sleep.
Meta Description: [ For travellers looking to skim a few dollars off their travel expenses, why not consider sleeping in the airport, train station and other strange places you would never normally consider? It's free! ]
American Airlines Mobile - Day of Travel, View Reservation, Flight Check-In, Flight Status.
2. Reservations, Book Flights, Change Flights, Fare Sales & Special Offers. 3. Travel Information,
Flight Status,View/Delete Notification, Create Flight Status Notification.
4. AAdvantage, View My Miles, Enroll in AAdvantage
Request Upgrades, Buy 500 Mile Upgrades.
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