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UPPCS Environment Gap Sheet: Greenhouse Gases and the Ozone Layer.

UPPCS has asked 14 of these. 6 have not been asked yet. Lock the first list, then read the second: it holds what UPPCS has not used yet.

First, the concept

Sunlight warms the Earth; the Earth gives the heat back as infrared rays. Greenhouse gases absorb part of it and keep the planet warm. More of these gases means more warming.

The ozone layer is a different story: it sits in the stratosphere (about 15–35 km up) and blocks harmful ultraviolet (UV-B) rays. CFCs break it down.

Ozone near the ground is a pollutant and a greenhouse gas. Ozone high up is a shield. UPPCS likes this contrast.

✅ Already asked (14)

The gases

  • Carbon dioxide · The main human-made greenhouse gas; over 420 ppm now
  • Methane · Paddy fields, cattle, landfills; traps far more heat than CO₂
  • Nitrous oxide · From nitrogen fertilisers
  • Water vapour · The most plentiful greenhouse gas
  • CFCs and HFCs · Refrigerants; CFCs harm ozone, HFCs only warm the planet
  • Not greenhouse gases · Nitrogen, oxygen and argon

Warming ideas

  • Global Warming Potential · Heat trapped by a gas compared with CO₂ over 100 years
  • Carbon sink · Oceans are the largest; forests and soil also store carbon
  • Coral bleaching · Warm water makes corals throw out their algae and turn white
  • Albedo · How much sunlight a surface reflects; snow high, forest low

Ozone layer

  • Ozone hole · Over Antarctica, in spring (September–October)
  • Ozone-depleting substances · CFCs, halons, carbon tetrachloride, methyl bromide
  • UV-B rays · Skin cancer, cataract, weak immunity
  • World Ozone Day · 16 September (Montreal Protocol was signed on this day in 1987)

❌ Not asked yet (6)

Items marked 'asked in other exams' have come in UPSC or other state exams, not yet in UPPCS.

🔒 6 items not asked yet

The gases: 1 · Warming ideas: 3 · Ozone layer: 2

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⚠️ The ozone hole is over Antarctica, not the Arctic. CFCs harm the ozone layer; HFCs do not, but they warm the planet. Argon is not a greenhouse gas.

'Asked' and 'not asked' are checked against every UPPCS question on this site. 'Not asked yet' does not mean it will surely come.

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