UPSC STATIC QUIZ – Geography : 16 April 2024

Solution: b)

Lightning is a very rapid — and massive — discharge of electricity in the atmosphere, some of which is directed towards the Earth’s surface. These discharges are generated in giant moisture-bearing clouds that are 10-12 km tall. The base of these clouds typically lies within 1-2 km of the Earth’s surface, while their top is 12-13 km away. Temperatures towards the top of these clouds are in the range of minus 35 to minus 45 degrees Celsius.

As water vapour moves upward in the cloud, the falling temperature causes it to condense. Heat is generated in the process, which pushes the molecules of water further up.

As they move to temperatures below zero degrees Celsius, the water droplets change into small ice crystals. They continue to move up, gathering mass — until they are so heavy that they start to fall to Earth.

This leads to a system in which, simultaneously, smaller ice crystals are moving up and bigger crystals are coming down.

Collisions follow, and trigger the release of electrons — a process that is very similar to the generation of sparks of electricity. As the moving free electrons cause more collisions and more electrons, a chain reaction ensues.

This process results in a situation in which the top layer of the cloud gets positively charged, while the middle layer is negatively charged. The electrical potential difference between the two layers is huge — of the order of a billion to 10 billion volts. In very little time, a massive current, of the order of 100,000 to a million amperes, starts to flow between the layers.

An enormous amount of heat is produced, and this leads to the heating of the air column between the two layers of the cloud. This heat gives the air column a reddish appearance during lightning. As the heated air column expands, it produces shock waves that result in thunder.

Solution: b)

Statement 3 is incorrect.

The thermocline layer lies below the first layer and is characterised by rapid decrease in temperature with increasing depth.

In the Arctic and Antarctic circles, the surface water temperatures are close to 0° C and so the temperature change with the depth is very slight. Here, only one layer of cold water exists, which extends from surface to deep ocean floor.

The oceans in the northern hemisphere record relatively higher temperature than in the southern hemisphere. The highest temperature is not recorded at the equator but slightly towards north of it.

Solution: a)

Statement 1 is incorrect.

The Yarlung Tsangpo is the upper stream of the Brahmaputra River located in the Tibet Autonomous Region, China. It is the longest river of Tibet.

Originating at Angsi Glacier in western Tibet, southeast of Mount Kailash and Lake Manasarovar, it later forms the South Tibet Valley and Yarlung Tsangpo Grand Canyon before passing into the state of Arunachal Pradesh, India.

Downstream from Arunachal Pradesh the river becomes far wider and is called the Siang. After reaching Assam, the river is known as Brahmaputra. From Assam, the river enters Bangladesh.

When leaving the Tibetan Plateau, the River forms the world’s largest and deepest canyon, Yarlung Tsangpo Grand Canyon.

Solution: d)

The onset of the monsoon over Kerala marks the beginning of the four-month, June-September southwest monsoon season over India, which brings more than 70 per cent of the country’s annual rainfall. The onset of the monsoon is a significant day in India’s economic calendar.

Is it unusual for the monsoon to hit the Kerala coast early?

Neither early nor late onset of the monsoon is unusual, even though the forecast for this year is for earlier than would be usually expected.

Does an early onset foretell a good monsoon?

No, it does not — just as a delay does not foretell a poor monsoon. The onset is just an event that happens during the progress of the monsoon over the Indian subcontinent.

A delay of a few days, or perhaps the monsoon arriving a few days early, has no bearing on the quality or amount of rainfall, or its regional distribution across the country, during the four-month monsoon season.

And does a delayed onset mean cascading delays across the country?

A delay in onset over Kerala can potentially delay the arrival of the monsoon in other parts of the country, especially in the southern states, which normally start getting rain within days of the monsoon reaching the Kerala coast.

But again, a delayed onset over Kerala does not automatically or invariably mean delays in the arrival of the monsoon over the entire country.

Solution: b)

Bauxite is the ore which is used in manufacturing of aluminium. Bauxite is found mainly in tertiary deposits and is associated with laterite rocks occurring extensively either on the plateau or hill ranges of peninsular India and also in the coastal tracts of the country. Odisha happens to be the largest producer of Bauxite.