Aerosols can alter cloud properties

Aerosols are very important in the formation of clouds. Often aerosols act as Cloud Condensation Nuclei (CCN's), around which cloud droplets are formed. Without aerosols in the air, there would be far fewer clouds. Aerosols can also affect the properties of existing clouds. Recent studies have found that in the presence of high amounts of aerosols, clouds will have more droplets than normal, with droplets tending to be smaller than usual. Because the droplets are smaller and more numerous, the clouds last longer and are reflect sunlight better than before. This effect could have significant implications on the climate. As the clouds reflect more sunlight, less of the sun's energy reaches the surface of the earth, which then cools. This means that by putting more aerosols in the atmosphere, humans have the potential to alter the world's climate and cause global cooling.


Credit: Image credit: NASA Earth Observatory

For more info: http://www-sage3.larc.nasa.gov/solar/text/text-learning-aerosol.html