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Malti🕳️ Ozone Hole Formation — Antarctic Stratospheric Chemistry
Interactive Antarctic ozone hole simulation — CFC chlorine chemistry, polar stratospheric clouds and seasonal spring depletion in Dobson units.
This simulation models the seasonal formation and healing of the Antarctic ozone hole. CFC-derived chlorine catalytically destroys ozone, but only efficiently when polar stratospheric clouds form in extreme winter cold and spring sunlight returns to drive the chemistry — producing the characteristic August–October hole that heals by summer.
🔬 What It Demonstrates
A catalytic chlorine cycle destroys ozone, but only when two conditions overlap: cold enough temperatures (below −78°C) for polar stratospheric clouds, and returning sunlight to power the reactions.
🎮 How to Use
Pick a chlorine scenario, then drag the day-of-year slider (or let it auto-animate) to watch ozone drop through spring and recover by summer. Watch the thermometer badge for the PSC threshold.
💡 Did You Know?
One chlorine atom can destroy about 100,000 ozone molecules before leaving the stratosphere, which is why even trace CFC concentrations caused such dramatic depletion.
About the Ozone Hole Simulation
This canvas simulation recreates the physical chemistry behind the Antarctic ozone hole using a simplified, top-down polar-stereographic map. Chlorine atoms released from CFCs destroy stratospheric ozone through a catalytic cycle — Cl + O₃ → ClO + O₂, then ClO + O → Cl + O₂ — that regenerates the chlorine atom each pass, letting a single atom destroy roughly 100,000 ozone molecules over its stratospheric lifetime.
Crucially, this destruction only runs efficiently when two seasonal conditions overlap: extreme cold (below about −78°C) that lets polar stratospheric clouds form and activate the chlorine, and returning spring sunlight that drives the photochemical reactions. That is why the real ozone hole opens dramatically in August–October and heals by December–February, and why the simulation's ozone concentration (in Dobson Units) only drops sharply during that same window. The chlorine-level selector lets you compare the low pre-1980 baseline, the severe 1990s peak, and today's slowly recovering Montreal Protocol scenario.
Frequently Asked Questions
What does this simulation show?
It shows a simplified top-down view of Antarctica's stratospheric ozone layer, colour-mapped from purple/blue (severely depleted) to green/yellow (a healthy ~300 Dobson Units). As you move through the year, you can watch the ozone hole open in spring and close again by summer.
What are CFCs and how do they destroy ozone?
Chlorofluorocarbons (CFCs) are stable industrial gases once used in refrigerants and aerosols. In the stratosphere, ultraviolet light breaks them apart, releasing chlorine atoms. Each chlorine atom then catalyses ozone destruction without being consumed itself, so a small amount of chlorine can do enormous damage over time.
What is the catalytic destruction cycle?
A chlorine atom reacts with ozone (Cl + O₃ → ClO + O₂), then the resulting ClO reacts with a free oxygen atom (ClO + O → Cl + O₂). The chlorine atom comes out unchanged, ready to repeat the cycle — roughly 100,000 times before it is finally converted into a stable reservoir molecule and removed.
What are polar stratospheric clouds (PSCs) and why do they matter?
PSCs form only when stratospheric temperatures drop below about −78°C, which happens in the dark, extremely cold Antarctic winter. Their icy particle surfaces convert unreactive chlorine reservoir molecules into forms that can rapidly attack ozone once sunlight returns, making PSCs the key trigger for severe depletion.
Why does the hole only appear in spring?
Ozone destruction needs both PSCs (which require deep winter cold) and sunlight (which powers the photochemical reactions and keeps regenerating reactive chlorine). Winter has cold but no sunlight; summer has sunlight but no PSCs. Only spring (roughly August–October) has both together, which is exactly why the hole grows during that window and heals afterward.
What is the Montreal Protocol and is the ozone layer recovering?
The Montreal Protocol, signed in 1987, is an international treaty that phased out the production of CFCs and related ozone-depleting substances. Atmospheric chlorine levels have been slowly declining ever since, and the Antarctic ozone hole is on a gradual, measurable path to recovery, with full recovery to 1980 levels projected around the 2060s.
What do the controls do?
The chlorine-level selector switches between a low pre-1980 baseline, the severe 1990s peak (about four times higher), and today's Montreal Protocol recovery scenario (about twice the baseline and slowly falling). The day-of-year slider (or auto-animate toggle) moves through the seasons, and the thermometer badge shows the live stratospheric temperature against the −78°C PSC threshold.
What counts as an "ozone hole"?
Scientists define the ozone hole as the region where total column ozone drops below 220 Dobson Units, a threshold chosen because natural variability rarely pushes ozone that low without chemical depletion. The simulation's info bar reports the minimum Dobson Unit value reached as you move through the year.
Interactive Antarctic ozone hole simulation — CFC chlorine chemistry, polar stratospheric clouds and seasonal spring depletion in Dobson units.
2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install