the mesosphere
noun [ S ] environment specialized uk/ˈmes.əʊ.sfɪər/ us/ˈmez.oʊ.sfɪr/
散逸层（离地球表面50至100公里的大气层的一部分）
the layer of gases surrounding the earth at a height of between 50 and 100 kilometres
Compare: the exospherethe ionospherethe stratospherethe thermospherethe troposphere