What process occurs when oxides of nitrogen contribute to acid rain formation?

The formation of acid rain involves the interaction of oxides of nitrogen with water in the atmosphere, which leads to the production of nitric acid. When nitrogen oxides (NO and NO₂) are emitted, they can react with water vapor in the air. This reaction leads to the formation of nitric acid (HNO₃), which is a strong acid. When rain falls, this acid dissolves in the water droplets, resulting in rainwater that has a lower pH, thus categorizing it as "acid rain."

Understanding this process is crucial because it underscores the environmental impact of nitrogen oxides, which often stem from automotive exhaust and industrial emissions. The contribution of nitric acid to acid rain is significant because it can have detrimental effects on ecosystems, soil, water bodies, and even man-made structures.