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The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.
The temperature of the thermopause could range from nearly absolute zero to 987.547 °C (1,810 °F). Below this, the atmosphere is defined to be active [ clarification needed ] on the insolation received, due to the increased presence of heavier gases such as monatomic oxygen.
The lower part of the thermosphere, from 80 to 550 kilometres (50 to 342 mi) above Earth's surface, contains the ionosphere. The temperature of the thermosphere gradually increases with height and can rise as high as 1500 °C (2700 °F), though the gas molecules are so far apart that its temperature in the usual sense is not
Hypersonic flow is a high energy flow. [12] The ratio of kinetic energy to the internal energy of the gas increases as the square of the Mach number. When this flow enters a boundary layer, there are high viscous effects due to the friction between air and the high-speed object.
The high temperatures prevalent in the thermosphere (800–1000 K) have not been explained yet; [19] existing models predict a temperature no higher than about 400 K. [16] They may be caused by absorption of high-energy solar radiation (UV or X-ray), by heating from the charged particles precipitating from the Jovian magnetosphere, or by ...
The mesosphere (/ ˈ m ɛ s ə s f ɪər, ˈ m ɛ z-, ˈ m iː s ə-,-z ə-/; [1] from Ancient Greek μέσος (mésos) 'middle' and -sphere) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases.
This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion); the top of the stratosphere has a temperature of about 270 K (−3°C or 26.6°F). [9] [page needed]
The matter in the external part of the solar atmosphere is in the state of plasma, at very high temperature (a few million kelvin) and at very low density (of the order of 10 15 particles/m 3). According to the definition of plasma, it is a quasi-neutral ensemble of particles which exhibits a collective behaviour.