Soru

### Seasonal Antarctic Ozone Decrease

Two scientists present opposing viewpoints on the primary cause of the seasonal decrease in stratospheric ozone ($O_3$) concentration over Antarctica.

Scientist 1

The seasonal decrease in stratospheric ozone over Antarctica is primarily caused by chemical reactions involving chlorine-containing compounds, specifically chlorofluorocarbons (CFCs). During the dark polar winter, polar stratospheric clouds (PSCs) form. Chemical reactions on the surfaces of PSC ice crystals convert inactive reservoir species of chlorine into highly reactive forms, such as chlorine gas ($Cl_2$). In the spring, sunlight returns and photolyzes these molecules, releasing free chlorine atoms ($Cl$). These chlorine atoms act as catalysts, rapidly destroying ozone molecules in a cycle that requires sunlight. Therefore, the ozone hole is a direct result of anthropogenic chemical emissions.

Scientist 2

The seasonal ozone decrease is primarily a dynamic meteorological phenomenon caused by atmospheric wind patterns and temperature changes, rather than chemical destruction. During winter, a strong polar vortex isolates the air mass over Antarctica, preventing warmer, ozone-rich air from lower latitudes from mixing with polar air. Because the stratosphere over Antarctica gets extremely cold, the air descends, which naturally compresses and thins the ozone layer. Additionally, periodic increases in solar activity release high-energy particles that produce nitrogen oxides ($NO_x$) in the upper atmosphere. These nitrogen oxides naturally destroy ozone when they descend into the stratosphere. Thus, the seasonal ozone minimum is driven by natural cycles of solar radiation and atmospheric dynamics.

Scientist 1 and Scientist 2 differ in their views regarding which of the following points?