/aɪˈɒnəsfɪə(r) ||; aɪˈɑnəˌsfɪr/noun [sing] the ionosphere the layer of the earth's atmosphere between about 80 and 1000 kilometres above the surface of the earth, that sends radio waves back around the earth 电离层（大气层的组成部份，离地球表面约80至1000公里，反射无线电波） ☞Compare stratosphere and troposphere. 与stratosphere及troposphere比较。