The transport of air from the troposphere to the stratosphere over the eastern Mediterranean Sea and the neighboring countries up to the Black Sea is investigated, using a trajectory model and analyzed winds from the European Centre for Medium-Range Weather Forecasts. It is found that in summer the upper troposphere in this region is influenced by both westerly winds in the Polar Front Jet (PFJ) and southerly winds at the western flank of the upper level anticyclones over the Arabian and Asian heat lows. The convergence of these airflows accelerates the horizontal wind and increases the horizontal and vertical wind shear, creating a jet streak within the Subtropical Jet Stream (STJ) and deep tropopause folds. Clear-air turbulence, caused by horizontal deformation and the vertical wind shear along the STJ, and consequently turbulent mixing of tropospheric and stratospheric air near the tropopause region, appears to contribute strongly to the cross-tropopause transport over the eastern Mediterranean in summer.