Final answer:
Photochemical smog is predominantly found in urban areas, where high concentrations of vehicles and industrial activities, coupled with warm, sunny, and dry climates, contribute to its formation.
Step-by-step explanation:
Photochemical smog is a type of air pollution characterized by a mixture of pollutants which include nitrogen oxides (NOx) and volatile organic compounds (VOCs). These pollutants undergo chemical reactions in the presence of solar radiation, typically forming a brown haze predominantly seen above urban areas. This is due to the high concentration of vehicles and industrial activities that emit these pollutants in such environments. It occurs more frequently in urban settings with warm, sunny, and dry climates where stagnant air allows pollutants to accumulate.
Contrastingly, rural areas, which are typically characterized by agriculture and less dense populations, do not have the same concentration of pollution sources and therefore photochemical smog is less common. Additionally, the presence of vegetation in rural areas can help to mitigate air pollution by absorbing some of the pollutants.
In summary, photochemical smog is found primarily in A. urban areas where the combination of human activity and climatic conditions favor its formation.