the troposphere
noun/ðə ˈtrɒpəsfɪə(r)/
/ðə ˈtrəʊpəsfɪr/, /ðə ˈtrɑːpəsfɪr/
[singular] (specialist)- the lowest layer of the earth’s atmosphere, between the surface of the earth and about 6–10 kilometres above the surface
对流层（大气的最低层，在地球表面和 6 至 10 公里上空之间） Word Originearly 20th cent.: from Greek tropos ‘turning’ + sphere.