This session is interested in the dynamical two-way interaction between the stratosphere and the troposphere, the mechanisms for this interaction, and its consequences for explaining both short-term atmospheric weather and longer-term climate variability. This also includes work that investigates alternate diagnostics for the definition of major and minor stratospheric sudden warmings and work that focuses on the role of the stratosphere for the predictability of tropospheric forecast in medium-range to sub-seasonal time scale.