निम्नलिखित कथनों पर विचार कीजिए :
- I.वायुमंडल के बिना भूपृष्ठ पर सर्वत्र तापमान हिमांक के बहुत नीचे होता है।
- II.वायुमंडल के द्वारा अवशोषित और पाशित (ट्रैप्ड) ऊष्मा हमारे ग्रह के औसत तापमान को बनाए रखती है।
- III.वायुमंडल की कार्बन डाइऑक्साइड जैसी गैसें विकिरण को अवशोषित और पाशित करने के लिए विशेष रूप से उत्तम हैं।
उपर्युक्त कथनों में कौन-कौन से सही हैं?
Read this question in English
Consider the following statements:
I. Without the atmosphere, temperature would be well below freezing point everywhere on the Earth's surface.
II. Heat absorbed and trapped by the atmosphere maintains our planet's average temperature.
III. Atmosphere's gases, like carbon dioxide, are particularly good at absorbing and trapping radiation.
Which of the statements given above are correct?
(a) I and III only · (b) I and II only · (c) I, II and III · (d) II and III only
उत्तर और व्याख्या · explanation in English
Answer: (c) I, II और III
All three describe the natural greenhouse effect. The Earth's surface re-radiates sunlight as infrared heat; gases such as carbon dioxide, methane and water vapour absorb much of it, which keeps the global average near 15°C. Remove that blanket and the surface would be about 33°C colder, below freezing.
- ✓ I Without the atmosphere's greenhouse effect the average surface temperature would fall by roughly 33°C, from about 15°C to around −18°C, too cold for life.
- ✓ II The heat that the atmosphere absorbs and traps is what holds the planet's average temperature at a life-supporting level.
- ✓ III Carbon dioxide, methane and water vapour absorb the infrared heat re-radiated by the surface and stop it escaping to space.
Remember · Natural greenhouse effect: CO2, CH4, water vapour trap outgoing infrared; keeps Earth ≈ 15°C instead of ≈ −18°C (a 33°C difference).
📘 Read it in NCERT: Class 9 Exploration, Ch 13 (practise this chapter)
Sources
- NCERT Class 9 · Exploration, Chapter 13 “Greenhouse gases like CO2, CH4 and water vapour absorb this re-radiated heat, preventing it from escaping into space. Without the atmosphere, the Earth would be too cold for life to survive.”
- NASA Science: What is the greenhouse effect? ↗ “If carbon dioxide were removed, the terrestrial greenhouse effect would collapse, and Earth's surface temperature would drop significantly, by approximately 33°C (59°F). … Part of what makes Earth so amenable is its natural greenhouse effect, which maintains an average temperature of 15 ° C (59 ° F) .”
Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·