mesosphere

https://doi.org/10.1351/goldbook.M03855
That region of the atmosphere which lies above the @S06042@ (about \(4752\ \text{km}\)) and below the @M03848@ (about \(8090\ \text{km}\)) and in which temperature decreases with increasing height; this is the region in which the lowest temperatures of the atmosphere occur.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2201 [Terms] [Paper]