Characteristics and Importance of the mesosphere layer
The mesosphere layer is the third layer of the atmospheric envelope, It is the middle layer, It is the coldest one, The atmospheric pressure in the mesosphere layer decreases as we go up, until it becomes 0.01 mb, at its top.
The mesosphere layer
The mesosphere layer extends from the stratopause (at a height of 50 km above the sea level) to the mesopause (at a height of 85 km above the sea level). The thickness of the mesosphere layer is 35 kilometres.
The temperature in the mesosphere layer decreases with a rate as we go up until it reaches (- 90 degrees Celsius) at its top. So, it is called the coldest layer.
The mesosphere layer contains limited quantities of helium and hydrogen gases only, So, It is highly rarefied.
The mesosphere layer protects the planet Earth from the celestial rocky masses that enter the atmospheric envelope of the Earth, where they burn as a result of their friction with the air molecules and forming luminous meteors.
Although the meteors are burnt in the mesosphere layer, the spaceships can not burn during their passing in it as their conical fronts disperse the heat and their tails are made of insulating material.
In the mesosphere layer, The temperature decreases with increasing height, due to decreasing absorption of solar radiation by the rarefied atmosphere and increasing cooling by CO2 radiative emission, the top of the mesosphere layer, called the mesopause, is the coldest part of Earth’s atmosphere, varying according to the latitude and the season.
The term near space is sometimes used, This term does not have a technical definition, but typically refers to the region of the atmosphere up to 100 km, roughly between the Armstrong limit (above which humans need a pressure suit to survive) up to the Kármán line where astrodynamics must take over from the aerodynamics in order to achieve flight.