Final answer:
Chemical reactions on Polar Stratospheric Clouds involving chlorine and bromine lead to the depletion of the ozone layer. This process is heightened by the photolyzation of ozone-forming and ozone-destroying radicals propped by the sunlight in the Chapman Cycle. International agreements have reduced the production of CFCs, aiding in the recovery of the ozone layer.
Step-by-step explanation:
The reactions that happen on Polar Stratospheric Clouds (PSCs) are critical to understanding ozone layer depletion. PSCs form over Antarctica during the winter, trapping chlorine and nitric acid. In the spring, the clouds melt and release halogenated compounds into the stratosphere, where the sunlight photolyzes them, freeing halogen radicals that destroy ozone in a process known as the Chapman Cycle.
The first step in the Chapman Cycle is when ultraviolet rays from the Sun photolyze an oxygen molecule (O₂), creating two oxygen radicals (O). These radicals then combine with another oxygen molecule to form ozone (O₃). Ozone molecules absorb UV radiation to convert back into an oxygen molecule and an atomic oxygen atom, which can further recombine to reform oxygen molecules. The interaction between UV light and ozone not only protects the Earth from UV radiation but also warms the stratosphere.
However, substances like CFCs and HCFCs used in industrial processes release chlorine and bromine when broken down by solar radiation, initiating a chain reaction that destroys ozone molecules. This is crucial as one chlorine molecule can destroy up to 100,000 ozone molecules. The depletion of ozone by these radicals leads to the formation of the ozone hole.
It's essential to note that due to international efforts and agreements like the Montreal Protocol, the production of CFCs has ceased, which has halted the growth of the ozone hole and started the process of recovery. This demonstrates the effectiveness of global cooperation in addressing environmental issues.