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The upper atmosphere is the thermosphere, extending from 56 miles to 375 miles above Earth. It is very hot but has low air density. The exosphere, which merges with space, has even lower air density and is home to auroras.
The upper atmosphere is generally considered to be the region of the thermosphere, which is the thin outer layer of Earth’s atmosphere that begins about 56 miles (90 kilometers) and extends out to about 375 miles (604 kilometers). Spacecraft such as the International Space Station (ISS) or the United States Space Shuttle typically orbit in the upper atmosphere at a distance of about 140 miles (225 kilometers). In contrast, commercial aircraft travel in the much lower level stratosphere extending to a maximum height of 31 miles (50 kilometers) where the earth’s ozone layer exists.
While the concentration of the air of Earth’s upper atmosphere in the thermosphere region is very small compared to what people experience at the Earth’s surface, this atmosphere is also very hot due to the radiation it receives from the Sun. Estimates for atmospheric gases in the upper thermosphere they warm up to 3,600° Fahrenheit (2,000° Celsius). Due to the rarity of atmospheric gases at this level, however, their heat is not conveyed to objects passing through the region.
A fifth layer of the upper atmosphere that merges with the vacuum of space and is often not considered part of the actual atmosphere is the exosphere. The air density of the exosphere is extremely low and the region extends from approximately 375 miles (604 kilometers) to 6,200 miles (9,978 kilometers). The exosphere merges with regions of the Van Allan radiation belt above it, an area of highly charged magnetic particles generated and held in place by the Earth’s magnetic field. The exosphere is so thin that there is only about one atom of air or hydrogen per cubic centimeter of space in the higher regions, and more than 50% of those molecules eventually escape into space. The region is used for many low-orbiting satellites that are unaffected by rarefied gases.
One of the unique aspects of the upper atmosphere is that it is the home of auroras, such as the aurora borealis and aurora australe, or the aurora borealis and aurora borealis, which are most clearly visible within 10°-20° of latitude from the South Pole. The lights are generated by the magnetic effects that the Earth generates when it interacts with the solar wind and atmospheric gases at this level. The colors that the lights show in the upper atmosphere depend on the type of air molecules being hit, with the green to brownish-red colors being produced by oxygen, the blue by ionized nitrogen, and the red by single-state nitrogen. lower energy.
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