They update their world map of smoke and other aerosols and put it on the TOMS web site for everyone to see. A series of TOMS aerosol maps which shows the changing distribution of smoke from Western wildfires between July 31 and August 2, 2000. Aerosols absorb light. So by looking at sunlight reflected from the Earth, scientists can see where pollutants are. But it's not quite that simple.
Clouds absorb light, too.
But TOMS solves the problem by looking at two different wavelengths of light. Wavelength is what gives light color. Blue light has a shorter wavelength than red light. TOMS sees light that has a very short wavelength, so short that we can't see it with our eyes. The wavelengths TOMS uses are both absorbed by clouds, but the aerosols only absorb the shorter wavelength.