Heating Up the Atmosphere (Animation) - When soot absorbs sunlight, it heats the air and reduces the amount of sunlight reaching the ground, cooling the Earth's surface. The heated air makes the atmosphere unstable, creating rising air (convection) that forms clouds and brings rainfall to regions that are heavily polluted. The increase of rising air is balanced by an increase in sinking air (subsidence) and drying. When air sinks, clouds and thus rain, cannot form creating dry conditions. Soot or black carbon is the product of low temperature burning. It is generated from industrial pollution, traffic, outdoor fires and household burning of coal and biomass fuels. Note: This is the standard definition version of the Soot Effects Rainfall animation MPEG. Animator: Susan Twardy (HTSI). Writer: Rani Chohan (NASA/GSFC).