Past exam of the chemistry course of the year 4 of the natural sciences course of the University of Cambridge / 2021 / Interdisciplinary paper IDP1 / 1 / d / ii / Solution

Outside the cold polar activation regime, cooling generally slows temperature-activated gas-phase ozone destruction and can increase ozone if other conditions are held fixed. This is a weaker, less universal conclusion in the lower stratosphere because transport and imported ozone are important. Enhanced sulfate-surface activation or unusually cold cloud-forming air can instead activate chlorine and reverse the purely gas-phase tendency. Distinguish a local chemical cooling effect from the dynamical response of the midlatitude ozone-column photolysis shielding.