Aerosols can also seed clouds. Introducing anthropogenic aerosols to a cloud typically results in more--and smaller--cloud droplets. This tends to suppress precipitation and causes clouds to persist longer. The extra droplets also scatter more light, making aerosol-polluted clouds appear brighter than their pristine counterparts. NASA research has shown, however, that the effect can vary depending on the type of aerosol involved.
Image Information: Astronauts took this image, which shows a series of mature thunderstorms over Brazil, from the Space Shuttle. For more details, please visit this Gateway to Astronaut Photography page. Credit: NASA/Johnson Space Flight Center/Image Science & Analysis Laboratory
--Adam Voiland, Goddard Space Flight Center