Q.1) Tropical cyclones are a recurrent climatic phenomena in India. Discuss the origin and movement of tropical cyclones that originate in the Bay of Bengal.
The Top Answer for this question is written by – Nishant
Ans) Tropical Cyclones are fast rotating wind systems with a low pressure centre. 80% of cyclones in Indian subcontinent originate in the Bay of Bengal (BOB). Such cyclones either develop in situ over the BOB and adjacent Andaman Sea or are remnants of typhoons from Northwest Pacific Ocean crossing over China Sea. Reasons for their origin in BOB are:
1. Bay of Bengal has relatively calm sea surface and consistent high temperatures above 27 Celsius
2. Lying upwards of the ITCZ , BOB has the right mix of existing low pressure with
adequate Coriolis force
3. There is upper air divergence and low wind shear at BOB latitudinal range
Movement of Tropical Cyclones in Bay of Bengal:
– Move from east to west in anti-clockwise direction
– Odisha and Andhra Pradesh are the worst hit areas
Bay of Bengal is known to produce more cyclones both in number and intensity compared to Arabian Sea. Reasons vary from a colder Arabian Sea to influence of south-west monsoon winds in the region. Also, BOB is east-lying and receives more remnants of typhoons carried over by easterly trade winds. The cyclone Phallin in 2013 was an example of severe cyclone in BOB region.
Q.2) What do you understand by an El Nino year? Also explain the mechanism of its occurrence. How does it affect the Indian subcontinent?
The Top Answer for this question is written by – Vikrant Madhusudhan Parab
Ans) El-nino means reversal of Walker cell(cell that moves from Peruvian coast to Western Pacific Pool near Australia).
In normal year there is High pressure at Peruvian coast and LP at WPP and wind moves from HP to LP, thus there is upwelling at Peruvian coast and down-welling at WPP. When this entire phenomenon is reversed it is called as El-nino year.
How it affect Indian Subcontitnet-
1.)Wind always move form High pressure to Low pressure. Indian subcontinent monsoon is depended on ITCZ(near Tibet) where there must be LP and Mascarene High(near Madagascar) where there must be HP so that wind moves from HP to LP and carries water-vapour(while moving over Ocean) with it and gives rainfall. Thus, for good monsoon in India this condition must be satisfied.
2.)But , what if there is LP at Madagascar then wind wont flow towards ITCZ and thus it wont carry water-vapour and thus less rainfall. LP is generated at Madagascar since HP is generated at Western Pacific Pool due to El-nino(reason unknown).
3.)Because of all this there is less rainfall in India and it creates Draught situation in India and it results in Less Agro Productivity, inflation, etc.
So , this is how Sub-continent which is depended on Monsoon is affected by external reasons like El-nino.
Q.3) What are the conditions required for good production of wool? Examine the reasons behind Australia leading in wool production but not in textiles.
The Top Answer for this question is written by – Monk Who Sold his Nano
Ans) Wool is obtained from fleece of fur bearing animals. So conditions that can support these animals in abundance would suffice for good production of wool. These condition include-
availability of pastures – The reason why pastoralists have to keep on migrating.
climate – different animals are adapted to different conditions eg-yak(cold), sheep (temperate), mink (Siberia)
Scientific advancements advanced genetic breeding, veterinary services etc.
Reasons for Australia being leading producer are-
1) 80% of it’s ships are merino(a cross of 3 strains: Peppin, South Australian and fine-wool Saxon)- Due to selective breeding pressure they have acquired certain characteristics like heavy fleeces of fine quality wool.
2) Small population with small agricultural needs- so there’s very little agricultural pressure over the vast meadows of Downs, and vast pastures are available for sheeps to graze.
3) The penal colony of Australia was coerced into sheep breeding, for wool demand back home.
4) R&D and government support
Woolen textile industry are market driven industry. Australia doesn’t present a good market with it’s small population and tropical climate. (even in India woolen textile centres are in north-Jalandhar, Ludhiana away from southern cotton textile centres). Besides wool is not weight loosing material. So there is no incentive to develop textile industry in Australia.
Q.4) Examine the reasons behind Brazil’s drought-story. As a District Magistrate of the drought-struck district, what will be your action-plan to mitigate the dangers of droughts?
The Top Answer for this question is written by – Santhosh Venkatesh
Ans) The 2015 Brazilian drought is an ongoing crisis affecting South-eastern Brazil including the heavily populated city of Sao Paulo.
Reasons for drought
Scientists believe that clouds take in water from Amazon rainforest via trees, rivers, soil thereby creating flying rivers in clouds. These flying rivers Transport water vapour from central Brazil containing Amazon to coastal areas such as Sao Paulo. Due to deforestation the flying rivers are disappearing.
Poor water management, high levels of water pollution, leakage of pipes and bad infrastructure have added woes to the problem.
Action plan to mitigate the dangers of droughts
Ensuring Food security
– Encourage farmers to grow hardy crops. Coordinate with NGO’s and FCI to ensure availability of grains for affected areas
– Ensure that drought resistant seeds are received by farmers on time.
Mitigate Water crisis
– After Consulting with State government initiate Rationing of water to ensure equality of water distribution.
– Encourage Rainwater harvesting and traditional water saving systems such as Johads and tanks
– Consult with IMD for collecting data about expected longevity of drought and discuss possibility of Cloud seeding as short term measure.
Along with these, steps must be taken for plugging leakages ,improving water management systems, increasing rural insurance penetration and creating awareness about effects of deforestation for a long term solution.
Q.5) Examine the causes behind the phenomena of ocean water circulation.
The Top Answer for this question is written by – Lalit Kishore
Ans) Ocean water circulation is a holistic phenomena caused by several interrelated,interdependent set of components as discussed below-
Planetary winds-Large bands of water current moves in the ocean like big rivers in a particular direction due to frictional force caused by planetary wind.Monsoonal winds changed the direction of north and south equatorial current.
Temperature-Temperature differentiation of oceanic water of equator and poles.Equatorial water is hot,light and rise,whereas cold water sinks and a circulation start from equator to poleward.
Salinity-Water of high salinity sinks and water of low salinity flows on the surface.
The earth’s rotation(Coriolis force)-The earth’s rotation deflect the direction of winds in clockwise and anticlockwise in northern and southern hemisphere respectively.For example Gulf stream and canaries current in northern hemisphere.
Land-A landmass obstruct and divert the water circulation.It depends on type of the continental shelf of continent and oceanic islands.For example west wind drift diverted northward as Peruvian current by southern tip of Chile.
Upwelling and downwelling-Upward movement of cold water as near the Peruvian coast and downward drift of water where salinity or density is high influence the water circulation as a whole system.
Ocean bottom topography-Ocean bottom topography also affect the circulation of oceanic water.Such as huge mid oceanic ridges in the Atlantic and Pacific ocean,seamounts,gyots.
Others-Temporary obstruction in the circulation by Tsunami caused by oceanic earthquake and Volcanoes,and El-Nino southern oscillation etc.At the same time tidal forces also influence the water level and hence circulation of water.
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