Ozone naturally decomposes to oxygen via photodecomposition. 2 o3(g) ® 3 o2(g) ∆erxn = -284. 4 kj/mol, ea = 17. 7 kj/mol the temperature of the lower stratosphere is typically around –80oc in winter, while increases to around –60oc in the summer. How much faster is the photodecomposition of ozone in the summer compared to the winter?.