Researchers studied how air moves between the stratosphere and troposphere in the Northern Hemisphere during winter. They compared different methods and found that while the overall pattern of air movement is similar, the exact amounts can vary greatly. Air mostly moves from the stratosphere to the troposphere in certain latitude regions, but at higher latitudes, the direction of air movement can change. The exchange of air between these layers does not always affect higher altitudes. The composition of the stratosphere may only be directly influenced by the exchange near the tropopause.