With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct ? 1. IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean. 2. An IOD phenomenon can influence an El Nino's impact on the monsoon. Select the correct answer using the code given below:
- A.1 only
- B.2 only
- C.Both 1 and 2
- D.Neither 1 nor 2
Correct answer
Explanation
The correct answer is B, 2 only. The Indian Ocean Dipole lies wholly within the Indian Ocean, and it can soften or strengthen El Nino's effect on the monsoon. The IOD is the difference in sea surface temperature between the western Indian Ocean, near the Arabian Sea and the African coast, and the eastern Indian Ocean, south of Indonesia. It is not measured against the eastern Pacific, which is where El Nino is tracked, so statement 1 is wrong. In a positive IOD the western part is warmer than usual and the eastern part cooler; this favours more rain over India. In a negative IOD the pattern reverses and the monsoon tends to weaken. Statement 2 is correct: a positive IOD can offset a drought-causing El Nino, as in 1997 and 2019, when India still got normal or above-normal rain. Option A is wrong because statement 1 wrongly brings in the Pacific. Option C is wrong because it accepts statement 1. Option D is wrong because statement 2 is true. Exam tip: IOD = west versus east Indian Ocean; El Nino = eastern Pacific; a positive IOD helps the Indian monsoon.
Practice Questions
View allWhich one of the following is applicable to collision-coalescence process of precipitation?
- A.Clouds which do not extend beyond the freezing level
- B.Clouds which extend beyond the freezing level
- C.All types of clouds
- D.Cirrocumulus cloud
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Collision-coalescence is the way rain forms in warm clouds, whose tops stay below the level where water freezes. In such clouds all droplets are liquid.
Read the full explanation →Identify the type of drainage pattern on the basis of the given characteristics :
1. It represents the most common pattern of streams and their tributaries
2. It occurs in areas of uniform rock type and regular slope
3. A map, or aerial photograph, shows a pattern like the veins on a leaf— smaller streams join the main stream at an acute angle
Select the correct answer.
- A.Dendritic
- B.Radial
- C.Trellis
- D.Centripetal
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A pattern that looks like the branches of a tree or the veins of a leaf, formed on uniform rock with a regular slope, is dendritic.
Read the full explanation →The Research Design and Standards Organization is the R&D wing of which one of the following organizations ?
- A.Bhabha Atomic Research Centre
- B.Indian Space Research Organization
- C.Indian Railways
- D.Defence Research and Development Organization
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The Research Design and Standards Organisation (RDSO) is the sole research and development wing of the Ministry of Railways. RDSO is headquartered at Lucknow.
Read the full explanation →Which one of the following Indian States has recorded negative growth population as per Census 2011?
- A.Manipur
- B.Mizoram
- C.Tripura
- D.Nagaland
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Nagaland was the only Indian state whose population fell between 2001 and 2011; its decadal growth rate in Census 2011 was about −0.6 per cent.
Read the full explanation →Piecing together the puzzle of geologic time to create and analyze historical maps of the Earth is known as
- A.paleoclimatology
- B.paleogeomorphology
- C.paleolithology
- D.paleogeography
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Paleogeography is the study of the Earth's geography in the geological past, and its main product is a set of maps showing where continents, oceans, mountains and shorelines lay at different times.
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