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GS Paper IUPSC Prelims 2001
Health & Medicine
Question No. 249Interactive Test Mode
00:00
+2-0.66

Q249. Cloudy nights are warmer compared to clear cloudless nights, because clouds:

Cloudy nights are warmer compared to clear cloudless nights, because clouds:

Select the correct option below (or cross out options to eliminate)
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Official Answer Key & Detailed Solution

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Official UPSC Answer KeyUPSC Prelims 2001 • Science and Technology

Correct Answer: Option (B) — reflect back the heat given off by earth

Concept & Option Breakdown

Standard Reference Verified

During the day, the Earth absorbs solar radiation, and at night it emits this heat back into space as longwave terrestrial radiation. Clouds act as a blanket by trapping and reflecting this outgoing infrared radiation back towards the Earth's surface, preventing radiative cooling and keeping cloudy nights warmer.

Elimination Heuristic & Exam Approach

Clouds act like greenhouse gases for terrestrial longwave radiation, reflecting and reradiating Earth's outgoing heat back downwards.

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Question Specifications & Syllabus Mapping

Examination & YearUPSC Civil Services Preliminary Examination 2001 (Q249)
Paper & Marking SchemeGS Paper I • 2 Marks (-0.66 Negative for incorrect response)
Syllabus Subject & TopicScience and Technology → Health & Medicine
Official Answer KeyOption (B) — reflect back the heat given off by earth

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Frequently Asked Questions — UPSC Prelims 2001 Q249

What is the official answer for UPSC Prelims 2001 GS Paper I Question 249 (Science and Technology)?

The official UPSC answer key for this 2001 Science and Technology (Health & Medicine) question is Option (B): "reflect back the heat given off by earth". Correct attempts carry 2 Marks with -0.66 Negative penalty for wrong answers.

Which UPSC Prelims syllabus topic does this 2001 question belong to?

This question belongs to GS Paper I under the subject "Science and Technology" and micro-topic "Health & Medicine". You can explore all repeated questions from Health & Medicine in Acme AI's 3D Prelims PYQ Realm or practice 50 full-length and sectional tests in the APT Prelims Test Series.

How can I solve this Health & Medicine UPSC Prelims question using option elimination?

Clouds act like greenhouse gases for terrestrial longwave radiation, reflecting and reradiating Earth's outgoing heat back downwards.

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