Chlorine Catalytic Ozone Destruction Cycle

Stratospheric Drivers

UV photolysis rate 50%

Active Cl catalysts 12

Reaction rate constant k 1.0×

Simulation speed 1.0×

Live Readouts

O₃ remaining

240 (100%)

Atomic O pool

Catalytic destructions (ClO+O→Cl+O₂ completions)

Avg. chain length per Cl atom

0.0

Legend

O₃ ozone molecule O atomic oxygen Cl free radical ClO bound intermediate

How it works

Chlorine atoms released from CFC photolysis destroy ozone through a two-step catalytic cycle — Cl is consumed in the first step and regenerated in the second, so a single atom can repeat the cycle thousands of times before it is finally sequestered:

Step 1:  Cl  + O₃ → ClO + O₂
Step 2:  ClO + O  → Cl  + O₂
Net:           O₃ + O  → 2 O₂   (Cl unchanged)

Ozone itself is normally replenished by the Chapman mechanism (O₂ + hν → 2O, then O + O₂ + M → O₃). UV photolysis in this model also breaks O₃ directly back into O + O₂, feeding the atomic-oxygen pool that both processes compete for. The catalytic cycle is destructive precisely because it intercepts that atomic oxygen in step 2 — every ClO + O event prevents an O + O₂ → O₃ recombination and frees the Cl to strike again.

UV photolysis rate — sets how fast O₃ splits into O + O₂, the atomic-oxygen source both the natural cycle and the Cl cycle depend on.
Active Cl catalysts — how many chlorine atoms (from CFC breakdown) are present; more catalysts run more parallel cycles at once.
Reaction rate constant k — a stand-in for the real Arrhenius temperature dependence of the Cl + O₃ and ClO + O steps (both run faster in the cold polar vortex).
Chain length — catalytic destructions divided by the number of active Cl atoms; in the real stratosphere one Cl atom can average roughly 10⁴–10⁵ ozone molecules before it is removed as HCl or ClONO₂, which is why trace CFC concentrations cause disproportionate ozone loss.

O₃ O Cl ClO

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