... Because of the Earth 's gravity, atmosphere is horizontally stratified (see, e.g., Kelley, 1989). Its structure can be organized by using the neutral gas temperature, as shown in the figure from mid-latitudes (note the logarithmic altitude scale). When going upward from the ground within the lowermost atmospheric region, troposphere, the temperature decreases up to about 10 km altitude (tropopause). ... Here the radiation also ionizes the neutral atmosphere, creating the ionosphere . ... 1989. ...