More About Aerosols
Desert Dust Bunnies?Aerosols from desert dust have an impact on climate. These large particles, comprised of minerals, are blown up so high in the atmosphere through intense dust storms that they don't fall back to earth as quickly as they would under ordinary circumstances. Some desert dust aerosols absorb solar radiation while other types scatter solar radiation. In addition to warming the atmosphere, desert dust aerosols may prevent the formation of storm clouds. Instead of a rain dance, it might be more helpful to perform an anti-aerosol dance.
How Aerosols Turn Darth Vader into Snow White
Natural aerosols tend to result in fewer but larger droplets in the clouds. By contrast, anthropogenic aerosols, like those released by ships, lead to a greater number, but smaller size, of cloud droplets (http://www.nytimes.com/2013/06/25/science/solar-boat-harnessed-for-research.html?partner=rss&emc=rss). These smaller droplets increase the reflectivity of the cloud, which means cooler temperatures. Unlike SSA and anthropogenic aerosols, aerosols from soil tend to be insoluble in water and consequently do not usually end up in rainwater.
It's a Bird, It's a Plane, It's a Contrail
Ships are not the only vehicles that affect clouds; airplanes form clouds from their contrails. The effects of airplane contrails are unknown, though scientists think their overall effect is to cool the earth. In the days following 9/11, when commercial flights were cancelled, the nights were hotter and the days were cooler33. We're not sure if contrails cool or heat the earth, but we know they do have some effect on weather and climate.
Contrails in October over the southeast United States. (Source)