Clouds and Air Quality

We have discussed how aerosols are important to the formation of clouds, but how do clouds affect air quality?

Clouds affect air quality in many ways. First, they provide a reactive environment in which literally thousands of chemical reactions take place at any one time. Second, certain cloud types serve as transport and deposition mechanisms that can carry the pollutants away from the surface to great heights aloft or deposit them at the earth's surface through precipitation. Finally, clouds affect the radiation budget of the earth due to their ability to absorb and re-emit radiation. We will now look briefly at a couple of the prominent cloud types and how they function in each of these roles.

As an exercise, consider returning to the Smog City simulator (don't forget to be patient while this code loads!). If you hit the "Reset" button, you will have the simulator at its pre-set settings. Now, try this experiment. What is the effect on the air quality index between the three cloud settings, shown to the right of the windmill? Click on each of the three cloud cover conditions (clear, partly cloudy, cloudy) and hit the "Start" button for each setting. Use your observations to answer the Quick Quiz question below.