Ozone Layer & UV Shield

Ozone Layer & UV Shield is a 3D atmospheric chemistry simulation of the stratospheric ozone column between 15 and 35 km altitude. Incoming solar radiation is separated into lethal UV-C (100 to 280 nm), sunburn-causing UV-B (280 to 315 nm), and low-energy UV-A (315 to 400 nm). Students watch triatomic ozone (O3) molecules split and recombine in the Chapman cycle to block 100% of UV-C and nearly all UV-B. Dragging or clicking chlorofluorocarbon (CFCl3) molecules releases reactive chlorine radicals (Cl and ClO) that catalytically strip oxygen atoms from ozone, dropping column thickness below the 220 Dobson Unit ozone-hole threshold and letting UV-B penetrate to the ground.

• Observe the three incoming wave beams at healthy ozone levels (~300 DU): purple UV-C stops high up, violet UV-B is blocked by O3, and amber UV-A passes through.
• Raise CFC emissions to 90% and set the Montreal Protocol year to 1995 to drop the ozone column below 220 Dobson Units and watch UV-B reach Earth.
• Click a green CFC molecule in the stratosphere to split off a reactive orange chlorine radical and watch it catalytically attack nearby O3 molecules.
• Slide the Montreal Protocol year forward from 2000 to 2065 to observe the gradual decay of stratospheric chlorine and recovery of the ozone shield.

1. 1Differentiate how the stratospheric ozone layer absorbs UV-C, UV-B, and UV-A solar radiation.
2. 2Describe how ozone is continuously created and destroyed by UV photons in the natural Chapman cycle.
3. 3Explain the catalytic mechanism by which a single chlorine radical from a CFC molecule destroys thousands of O3 molecules.
4. 4Interpret ozone column thickness in Dobson Units (DU) and evaluate the impact of the 1987 Montreal Protocol.

Questions teachers ask