The impact of aerosols on clouds, especially deep convective clouds (DCCs), is one of the most important and least understood aspects of climate change. Aerosols can either suppress or enhance convection/precipitation in DCCs under different conditions. Here we study the effect of vertical wind shear, a key atmospheric condition, on interactions between aerosol and DCCs. We show a dominant role by vertical wind shear in regulating aerosol effects on DCCs by both modeling and observational evidence. It qualitatively determines whether aerosols suppress or invigorate convective strength: aerosols always suppress convection under strong wind shear and enhance convection under weak wind shear until reaching an optimum loading. In a humid atmosphere, aerosols have the greatest potential to suppress convection when wind shear is strong.
Revised: December 9, 2009 |
Published: November 24, 2009