Atmosphere

Story hook

It is October 1985. Joseph Farman of the British Antarctic Survey is reading a printout from his Dobson spectrophotometer at Halley Bay, Antarctica. The reading he's looking at — total column ozone — should be ~300 Dobson units. It says 180. He double-checks. The instrument is fine. The reading is real. The sky above Antarctica has lost 40% of its ozone shield — the gas that absorbs the Sun's most lethal ultraviolet radiation, the gas that allows life to exist on land.

Farman's tiny paper in Nature (16 May 1985) sparks the fastest international environmental response in history. By September 1987, the world signs the Montreal Protocol phasing out CFCs. By 2024, the Antarctic ozone hole is beginning to close; full recovery is expected by 2065. It remains the only environmental treaty ratified by every country on Earth — and the only one to actually solve its problem.

The atmosphere is the thinnest, most fragile, most consequential layer of our planet. 78% nitrogen + 21% oxygen + 1% other; just 100 km between us and the vacuum of space (compared to Earth's radius of 6,371 km). Yet every weather event, every climate oscillation, every breath you take depends on its structure, chemistry, and motion. That structure is GS-I's atmosphere chapter.

Why this matters for UPSC

Syllabus location: GS-I — World Physical Geography (atmosphere composition + temperature + pressure + winds). Heavy Prelims weight — 3-5 questions yearly on atmospheric layers, gases, heat budget, pressure belts, winds. Mains stems link to climate change (GS-III), monsoon (GS-I), and disaster management.