Atmospheric gravity waves (GWs) significantly enhance vertical shear in the lowermost stratosphere (LMS), influencing turbulence and mixing in the extratropical transition layer. Using idealized baroclinic life cycle experiments with the ICON model, this study demonstrates that moisture and cloud processes amplify GW activity, driving strong shear and turbulence in the LMS. These findings highlight the critical role of GWs in shaping the dynamics in the LMS, particularly for clear air turbulence.