On polar-stratospheric-cloud surfaces at <~195 K: HCl + ClONO₂ → Cl₂ + HNO₃. Spring sunlight photolyses Cl₂, launching catalytic O₃ destruction that creates the Antarctic ozone hole.
On polar-stratospheric-cloud surfaces at <~195 K: HCl + ClONO₂ → Cl₂ + HNO₃. Spring sunlight photolyses Cl₂, launching catalytic O₃ destruction that creates the Antarctic ozone hole.