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GeographyMediumAsked in: CDS · CDS-I 2026, GK

Consider the following statements about the causes of ground surface inversion of temperature : 1. Ground surface inversion is also termed as radiation inversion. 2. The existence of negative lapse rate results in surface inversion. Which of the statements given above is/are correct?

  1. A.1 only
  2. B.2 only
  3. C.Both 1 and 2
  4. D.Neither 1 nor 2

Correct answer

C. Both 1 and 2

Explanation

The correct answer is C, Both 1 and 2. Both statements are correct: a ground inversion is formed by radiation cooling, and it is the same as a negative lapse rate near the surface.

Normally temperature falls with height at about 6.5 °C per 1,000 metres, the normal lapse rate. On long winter nights with a clear sky and still air, the ground loses its heat quickly by terrestrial radiation, and the air touching it cools faster than the air above. Temperature then rises with height for some distance, which is an inversion. Because it is caused by radiation from the ground, it is also called a radiation inversion. A lapse rate is negative when temperature increases upward, which is exactly this condition. Such inversions trap smoke and dust and cause fog and frost.

A is wrong because statement 2 is also correct. B is wrong because statement 1 is also correct. D is wrong because both statements describe a ground inversion correctly.

Exam tip: normal lapse rate 6.5 °C per km; an inversion is a negative lapse rate, favoured by long nights, clear skies, calm and dry air.

Practice Questions

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Q2.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements is/are correct? 1. Himalayan rivers have their origin in the snow-covered areas, hence are dry in winter season. 2. Rivers of the Peninsular Plateau have reached maturity. 3. Himalayan rivers depict all the three stages of normal cycle of erosion. Select the correct answer using the code given below.

  1. A.2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: C. 2 and 3 only

Himalayan rivers are perennial, so statement 1 is wrong, while statements 2 and 3 are correct. Himalayan rivers such as the Ganga, Indus and Brahmaputra rise from glaciers and snowfields and also get monsoon rain, so they flow all year round, including in winter.

Q3.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements related to latitude are true? 1. Rainfall, temperature and vegetation vary with latitude. 2. The difference between the longest day and the shortest day increases with latitude. 3. Indira Point is located approximately at 6°45' N latitude. Select the correct answer using the code given below.

  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: D. 1, 2 and 3

All three statements about latitude are true. Latitude decides how directly the Sun's rays strike a place, so temperature, rainfall and the type of vegetation change from the equator towards the poles, from hot, wet rainforests to cold tundra.

Q4.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following lakes is/are situated in Ladakh? 1. Tso Kar 2. Pangong Tso 3. Tsomgo 4. Tso Moriri Select the correct answer using the code given below.

  1. A.1 only
  2. B.2 and 3
  3. C.1, 2 and 4
  4. D.2 and 4 only
Show answer
Correct answer: C. 1, 2 and 4

Tso Kar, Pangong Tso and Tso Moriri are high-altitude lakes of Ladakh, while Tsomgo lies in Sikkim. Pangong Tso, at about 4,350 metres, is a long, narrow lake that stretches from Ladakh into Tibet, and most of its length lies on the Chinese side.