CLAES made the first global measurements of CFCs in the stratosphere. CFCs enter the stratosphere through upwelling in the tropics. The CFCs decrease with height as they are broken down by UV radiation. CFCs are the major source of stratospheric chlorine. Red indicates large amounts of CFC-12. Note: CFC-12 concentrations in the stratosphere as measured by CLAES. Animator: Barbara Summey (Raytheon). Scientist: Mark Schoeberl (NASA/GSFC). Platforms/Sensors/Data Sets: UARS/CLAES.