6.4.7—Ozone depletion effects
- Syllabus
- First assessment 2026
- Objective
- 6.4.7
- Level
- HL
Define an Ozone Hole by Concentration and Season
An ozone hole is a seasonal region of unusually low stratospheric ozone, especially over polar areas—not a literal opening in the atmosphere.
Polar stratospheric clouds support reactions that activate chlorine; spring sunlight drives rapid catalytic loss. The reduced shield raises surface UV and can affect health and ecosystems.
Antarctic spring measurements show a seasonal low-ozone area that expands and contracts rather than remaining a permanent hole.
A measured regional concentration anomaly over time, not a photograph or one day’s UV reading.
The ozone hole is not uniform global ozone disappearance; location and season are essential.