thermosphere

https://doi.org/10.1351/goldbook.T06338
Atmospheric shell extending from the top of the @M03855@ to outer space. It is a region of more or less steadily increasing temperature with height, starting at \(70\) or \(80\ \text{km}\). It includes the exosphere and most or all of the ionosphere (not the D region).
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2217 [Terms] [Paper]