Stratosphere

noun (uncountable, used with 'the')

/ˈstræt.ə.sfɪər/

The second layer of Earth's atmosphere, extending from the tropopause (approximately 12 km altitude) to about 50 km, characterised by increasing temperature with altitude (temperature inversion) due to absorption of ultraviolet radiation by the ozone layer (ozonosphere). The stratosphere contains roughly 90% of Earth's ozone, concentrated in the ozone layer between 15–35 km. In UPSC GS3, the stratosphere is examined in the contexts of ozone depletion by chlorofluorocarbons (CFCs) regulated under the Montreal Protocol, 1987, stratospheric aerosol injection as a geo-engineering proposal, and volcanic eruptions that inject sulphate aerosols causing temporary cooling.

✍️ Usage in a UPSC answer

India's phase-out of hydrochlorofluorocarbons (HCFCs) under the Kigali Amendment to the Montreal Protocol is expected to prevent an estimated 0.5°C of additional stratospheric ozone depletion by 2100, with co-benefits for climate through reduced GHG loading.

Synonyms

ozone layer (partial synonym)upper atmosphereozonosphere (subset)

Antonyms

tropospherelower atmosphere

🌱 Word Family

stratospheric (adjective), troposphere (noun), mesosphere (noun), ozone layer (noun phrase), tropopause (noun)

🔡 Root

Latin stratum = a spread layer, from sternere = to spread out; Greek sphaira = sphere, ball

📜 Etymology

Coined by French meteorologist Léon-Philippe Teisserenc de Bort around 1902, who used balloon soundings to identify the layer of the atmosphere above the convecting troposphere where temperatures stabilise and then increase. He combined Latin stratum (a layer, as in stratigraphy) with Greek sphaira (sphere).

🧠 Memory Hook

STRATO (layer/stratum) + SPHERE. The stratosphere is the layered sphere — imagine it like a geological stratum but in the sky. Its defining feature is the ozone layer, which acts like Earth's sunscreen: it 'spreads out' (stratum = spread) UV protection across the entire planet.

📝 Seen in UPSC Question Papers

Prelims 2018 — Chemistry
Prelims 2017 — Pollution

Real UPSC previous-year questions whose text uses “Stratosphere” — proof this word earns its place on your list.

🌿 Environment & Ecology 📖 Seen in: Ecology Fundamentals — Ecosystems, Foo...

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