Stratospheric Circulation Simulation

A slow, mean vertical circulation, called the Brewer-Dobson circulation, lofts air over the tropics from the troposphere into the stratosphere. Air lofted into the stratosphere then moves either to the north or the south where it drops back down to the troposphere, completing the circulation by moving back towards the tropics.

A second, faster, horizontal circulation is active in the stratosphere. This stratospheric circulation moves from east to west around the equator and changes directions to west-to-east towards the poles. The net result is that particles transported out of the tropics may cover the globe in only two months time.