It was estimated that the eruption of the Mount Pinatubo volcano resulted in the injection of 20 million metric tons of \(\mathrm{SO}_{2}\) into the atmosphere. Most of this \(\mathrm{SO}_{2}\) underwent oxidation to \(\mathrm{SO}_{3},\) which reacts with atmospheric water to form an aerosol. (a) Write chemical equations for the processes leading to formation of the aerosol. (b) The aerosols caused a \(0.5-0.6^{\circ} \mathrm{C}\) drop in surface temperature in the northern hemisphere. What is the mechanism by which this occurs? (c) The sulfate aerosols, as they are called, also cause loss of ozone from the stratosphere. How might this occur?

(a) The chemical equations for the formation of aerosols are: \(2\mathrm{SO}_2 + O_2 \rightarrow 2\mathrm{SO}_3\) (oxidation of SO₂ to SO₃) and \(\mathrm{SO}_3 + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{H}_2\mathrm{SO}_4\) (formation of sulfuric acid from SO₃ and H₂O). (b) Aerosols cause a drop in surface temperature by reflecting incoming solar radiation back into space due to their high albedo, reducing the sunlight that reaches the Earth's surface. (c) Sulfate aerosols might cause ozone loss in the stratosphere by providing a surface for chemical reactions that destroy ozone, such as: \(\mathrm{O}_3 + \mathrm{H}_2\mathrm{SO}_4 \rightarrow \mathrm{O}_2 + \mathrm{H}_2\mathrm{S}_2\mathrm{O}_8\) (ozone reacting with sulfuric acid to form molecular oxygen and persulfuric acid).