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GS Paper: GS1-15.Geographical features and their location- Changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

  • Revised height of Mount Everest

    Nepal and China jointly announced the new height of Mount Everest as 8,848.86 meters.

    8,848 metres — the answer to one of the most widely popular quiz questions, and a number drilled into the minds of school students around the world for decades, is set for a revision.

    Mt. Everest

    • Mount Everest or Sagarmatha, Earth’s highest mountain above sea level, is located in the Himalayas between China and Nepal -– the border between them running across its summit point.
    • Its current official elevation – 8,848.86m – places it more than 200m above the world’s second-highest mountain, K2, which is 8,611m tall and located in Pakistan-occupied Kashmir.
    • The mountain gets its English name from Sir George Everest, a colonial-era geographer who served as the Surveyor General of India in the mid-19th century.
    • Considered an elite climbing destination, Everest was first scaled in 1953 by the Indian-Nepalese Tenzing Norgay and New Zealander Edmund Hillary.

    Try this PYQ:

    Q.When you travel to the Himalayas, you will see the following:

    1. Deep gorges
    2. U-turn river courses
    3. Parallel mountain ranges
    4. Steep gradients causing land-sliding

    Which of the above can be said to be the evidences for the Himalayas being young fold mountains?

    (a) 1 and 2 only

    (b) 1, 2 and 4 only

    (c) 3 and 4 only

    (d) 1, 2, 3 and 4

    Everest’s first survey

    • The mission to measure the world’s highest peak was taken up on a serious note in 1847 and culminated with the finding of a team led by Andrew Waugh of the Royal Surveyor General of India.
    • The team discovered that ‘Peak 15’ — as Mt Everest was referred to then — was the highest mountain, contrary to the then-prevailing belief that Mt Kanchenjunga (8,582 m) was the highest peak in the world.
    • Another belief, prevailing even today, is that 8,840 m is not the height that was actually determined by the 19th-century team.
    • That survey, based on trigonometric calculations, is known as the Great Trigonometric Survey of India.

    Why is the height being revised?

    • The height of the summit, however, is known to change because of tectonic activity, such as the 2015 Nepal earthquake.
    • Its measurement over the decades has also depended on who was surveying.
    • Another debate is whether the height should be based on the highest rock point or the highest snow point.

  • Western Disturbances and winters in North

    For the past few days, Chandigarh and its neighbouring states have been experiencing unusually cold days although the night temperatures are normal.

    Try this PYQ:

    Consider the following statements:

    1. The winds which blow between 30°N and 60°S latitudes throughout the year are known as westerlies.
    2. The moist air masses that cause winter rains in the North-Western region of India are part of westerlies.

    Which of the statements given above is/are correct?

    (a) Only 1

    (b) Only 2

    (c) Both 1 and 2

    (d) Neither 1 nor 2

    Temperature anomaly in North

    • Meteorological officials have attributed the trend to the cloud cover in the region which was absent until a few days ago.
    • It is the result of a western disturbance, which has brought about a spell of precipitation in the northwest Himalaya.

    Role of clouds

    • During the day, clouds obstruct the heat from the sun from reaching the surface of the earth, reflecting some of it back into space.
    • This lowers the temperature. Cold winds blowing down from snow-bound areas in the mountains also contribute to the cooling effect.
    • At night, however, clouds act like blankets – they help retain some of the heat energy radiated back by the earth’s surface.
    • Overcast weather at night, thus, increases greenhouse warming.

    What are western disturbances?

    • In northern India, winter rains and clouds are generally caused by moisture-bearing wind systems called western disturbances.
    • They originate and gather moisture over the Mediterranean region and flow eastwards towards the Indian subcontinent.
    • When some of these winds run into mountains of the northwest Himalaya, they are forced upward.
    • At higher altitudes, the temperatures drop and water vapour gets condensed. This leads to cloud formation and eventually rain and snow.

    Other factors for severe winters in North

    • In north India, the huge temperature difference between summers and winters is due to its continentality (distance from seas and oceans).
    • Air from oceans moderates the temperature as it moves onshore, but this effect is missing in continental interiors.
    • As a result, north India has greater seasonal differences as compared to peninsular India.
    • Temperature also reduces rapidly with altitude, and thus, the Himalayan region is colder still.

  • Why has the Northeast Monsoon remained deficient this year?

    Rainfall over the Southern peninsular region has been deficient so far due to prevailing La Nina conditions according to the India Meteorological Department (IMD).

    Try this PYQ:

    Q.La Nina is suspected to have caused recent floods in Australia. How is La Nina different from El Nino?

    1. La Nina is characterized by unusually cold ocean temperature in equatorial Indian Ocean whereas El Nino is characterized by unusually warm ocean temperature in the equatorial Pacific Ocean.
    2. El Nino has an adverse effect on south-west monsoon of India, but La Nina has no effect on monsoon climate.

    Which of the statements given above is/are correct?

    (a) Only 1

    (b) Only 2

    (c) Both 1 and 2

    (d) Neither 1 nor 2

    What is the Northeast monsoon?

    • India receives rainfall during two seasons.
    • About 75 per cent of the country’s annual rainfall is received from the Southwest monsoon between June and September.
    • The Northeast monsoon, on the other hand, occurs from October to December and is a comparatively small-scale monsoon, which is confined to the Southern peninsula.
    • After the complete withdrawal of the Southwest monsoon from the country takes place by mid-October, the wind pattern rapidly changes from the south-westerly to the north-easterly direction.
    • Also called the winter monsoon, the rainfall associated with the Northeast monsoon is important for almost entire South India.

    Why it is important?

    • Tamil Nadu records about 48 per cent (447.4 mm) of its annual rainfall (943.7 mm) during these months, making it the key factor for undertaking agricultural activities and reservoir management in the state.
    • Some South Asian countries such as Maldives, Sri Lanka and Myanmar also record rainfall from October to December.

    Why there are distortions?

    • The majority of districts in Tamil Nadu remain highly rain-deficient up this time.
    • The period after the Southwest monsoon season, from October to December, is the peak time for cyclonic activity in the North Indian Ocean region — covering the Arabian Sea and the Bay of Bengal.
    • The winds associated with the formation of low-pressure systems, depressions, or cyclones influence this monsoon, and therefore, the rainfall.
    • Officials at IMD have linked it to the prevailing La Niña conditions in the Pacific Ocean.

    La Nina  link with the NE monsoon

    • While La Niña conditions enhance the rainfall associated with the Southwest monsoon, it has a negative impact on rainfall associated with the Northeast monsoon.
    • During La Niña years, the synoptic systems — low pressure or cyclones — formed in the Bay of Bengal remain significantly to the north of their normal position.
    • Besides, instead of moving westwards, these systems recurve. As they lie to the north of their normal position, not much rainfall occurs over southern regions like Tamil Nadu.

    Back2Basics: El Nino and La Nina

    • While El Niño (Spanish for ‘little boy’), the more common expression, is the abnormal surface warming observed along the eastern and central regions of the Pacific Ocean (the region between Peru and Papua New Guinea).
    • The La Niña (Spanish for ‘little girl’) is an abnormal cooling of these surface waters.
    • Together, the El Niño and La Niña phenomena are termed as El Niño Southern Oscillation (ENSO).
    • These are large-scale ocean phenomena which influence the global weather — winds, temperature and rainfall. They have the ability to trigger extreme weather events like droughts, floods, hot and cold conditions, globally.
    • Each cycle can last anywhere between 9 to 12 months, at times extendable to 18 months — and re-occur after every three to five years.
    • Meteorologists record the sea surface temperatures for four different regions, known as Niño regions, along this equatorial belt.
    • Depending on the temperatures, they forecast either as an El Niño, an ENSO neutral phase, or a La Niña.

  • Cyclone Nivar to make landfall in TN

    A developing cyclonic disturbance in the Bay of Bengal is expected to become a ‘severe cyclonic storm’ and make landfall in Tamil Nadu.

    Cyclone Nivar

    • The IMD has forecasted the development of a cyclone in the Southwest region of the Bay of Bengal, off Tamil Nadu coast.
    • It has said that it will strengthen into a cyclone. Once intensified, it would acquire its name ‘Nivar’, proposed by Iran.
    • After cyclone Gaja in 2018, this will be the second cyclone to cross Tamil Nadu in the last two years.

    Try this PYQ:

    In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?

    (a) Sea surface temperatures are low

    (b) Inter-Tropical Convergence Zone seldom occurs

    (c) Coriolis force is too weak

    (d) Absence of land in those regions

    Tropical Cyclone

    • A Tropical cyclone is an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
    • Cyclones are formed over slightly warm ocean waters. The temperature of the top layer of the sea, up to a depth of about 60 meters, need to be at least 28°C to support the formation of a cyclone.
    • This explains why the April-May and October-December periods are conducive for cyclones.
    • Then, the low level of air above the waters needs to have an ‘anticlockwise’ rotation (in the northern hemisphere; clockwise in the southern hemisphere).
    • During these periods, there is an ITCZ in the Bay of Bengal whose southern boundary experiences winds from west to east, while the northern boundary has winds flowing east to west.
    • Once formed, cyclones in this area usually move northwest. As it travels over the sea, the cyclone gathers more moist air from the warm sea which adds to its heft.

    Must read:

    [Burning Issue] Tropical Cyclones and India

  • Places in news: Mount Vesuvius

    The Italian Culture Ministry announced the discovery of well-preserved remains of two men, who perished during the volcanic eruption of Mount Vesuvius in 79 AD.

    Try this PYQ:

    Q.Consider the following statements:

    1. The Barren Island volcano is an active volcano located in the Indian Territory.
    2. Barren Island lies about 140 km east of Great Nicobar.
    3. The last time the Barren Island volcano erupted was in 1991 and it has remained inactive since then.

    Which of the statements given above is/are correct?

    (a) 1 only

    (b) 2 and 3 only

    (c) 3 only

    (d) 1 and 3 only

    Mount Vesuvius

    • Located in southern Italy near the coastal city of Naples, the 4,203-ft (1,281 metres) tall Vesuvius is the only active volcano in mainland Europe.
    • Vesuvius has been classified as a complex volcano (also called a compound volcano), one that consists of a complex of two or more vents.
    • It typically has explosive eruptions and pyroclastic flows –– defined as a high-density mix of hot lava blocks, pumice, ash and volcanic gas.
    • It has erupted more than 50 times and is considered among the most dangerous volcanoes in the world due to its proximity to Naples and surrounding towns.
    • Its last serious eruption, lasting two weeks, was in 1944 during World War II, which left 26 Italian civilians dead and around 12,000 displaced.

    The eruption of 79 AD

    • In 79 AD, the Roman Empire-era sister cities of Pompeii and Herculaneum were destroyed and buried during a catastrophic eruption of Vesuvius.
    • It was a catastrophic event that destroyed the ancient Roman city of Pompeii and killed around 16,000 people.
    • Pompeii, 8 km away from Vesuvius, served as a resort town on the Bay of Naples for Rome’s elite citizens, consisting of villas, cafes, marketplaces and a 20,000-seat arena.
    • In 63 AD, a major earthquake rattled the city, serving as a warning for the eruption to come. However, few residents bothered to abandon the region, known for its volatility.

  • Leonid Meteor Shower

    The Leonid meteor showers are currently making their yearly appearance and will reach their peak in India on November 17 and 18.  In August this year, there was another meteor called Perseids Shower.

    Try this question from CSP 2014:

    Q.What is a coma, in the content of astronomy?

    (a) Bright half of material on the comet

    (b) Long tail of dust

    (c) Two asteroids orbiting each other

    (d) Two planets orbiting each other

    What is Leonid Meteor Shower?

    • Meteor showers are named after the constellation they appear to be coming from.
    • The Leonids originate from the constellation Leo the Lion– the groups of stars which form a lion’s mane.
    • They emerge from the comet Tempel-Tuttle, which requires 33 years to revolve once around the Sun.
    • These meteors are bright and among the fastest moving– travelling at speeds of 71 km per second.
    • During this year’s showers, peaks of around 10 to 15 meteors are expected to be seen every hour.
    • The Leonid showers include fireballs– bright and large meteors than can last longer than average meteors, and “earthgazers”– meteors which appear close to the horizon with colourful and long tails.

    What is a meteor shower?

    • On its journey around the Sun, the Earth passes through large swathes of cosmic debris.
    • The debris is essentially the remnants of comets — great frigid chunks of matter that leave behind dirty trails of rocks and ice that linger long after the comets themselves have passed.
    • As the Earth wades through this cloud of comet waste, the bits of debris create what appears from the ground to be a fireworks display in the sky — known as a meteor shower.
    • Several meteor showers can be seen around the year. According to NASA, over 30 meteor showers occur annually and are observable from the Earth.

    Back2Basics:

  • Cyclonic storms during October

    October to December period is among the favourable months for the development of cyclones in the Bay of Bengal and the Arabian Sea. This year, however, October passed without witnessing a cyclonic storm.

    Must read: [Burning Issue] Tropical Cyclones and India

    https://www.civilsdaily.com/burning-issue-tropical-cyclones-and-india/

    When do cyclones form and hit Indian coasts?

    • About 80 cyclones are formed around the world annually, out of which five are formed in the Bay of Bengal and the Arabian Sea, together known as the North Indian Ocean.
    • India’s east and west coasts are prone to cyclones with the maximum associated hazards—rain, heavy winds and storm surge— faced by coastal districts of West Bengal, Odisha and Andhra Pradesh.
    • Cyclones in the North Indian Ocean are bi-modal in nature, that is, they occur during two seasons— April to June (pre-monsoon) and October to December (post-monsoon).
    • Of these, May and November remain the most conducive for the development of cyclones.

    When have cyclones skipped October, previously?

    • Cyclonic disturbances— either in the form of a well-marked low pressure, depression or a deep depression— are common in October.
    • Ocean disturbances enter the Bay of Bengal from the South China seaside and head towards the Indian coast.
    • IMD officials have attributed it to the weak La Nina conditions along the equatorial Pacific Ocean.
    • Cooler than normal sea surface temperatures over this region—termed as La Nina— has been prevailing since August this year.

    Madden Julian Oscillation (MJO)

    • Because Madden Julian Oscillation (MJO) was positioned in a favourable phase, the low-pressure systems intensified maximum up to a deep depression.
    • MJO is kind of an eastward-moving cyclic weather event along the tropics that influences rainfall, winds, sea surface temperatures and cloud cover. They have a 30 to 60-day cycle.
    • Most importantly, there was the high wind shear noted between the different atmospheric levels, last month.
    • The vertical wind shear— created due to significant wind speed difference observed between higher and lowers atmospheric levels— prevented the low-pressure systems and depression from strengthening into a cyclone.

  • Char-chaporis of Assam

    A proposed museum reflecting the “culture and heritage of the people living in char-chaporis” has stirred up a controversy in Assam.

    Do you know?

    Phumdis are a series of floating islands, exclusive to the Loktak Lake in Manipur. They cover a substantial part of the lake area and are heterogeneous masses of vegetation, soil and organic matter, in different stages of decay.

    What are char-chaporis?

    • A char is a floating island while chaporis are low-lying flood-prone riverbanks.
    • They are used interchangeably as they keep changing shapes — a char can become a chapori, or vice versa, depending on the push and pull of the Brahmaputra.
    • Prone to floods and erosion, these areas are marked by low development indices.
    • While Bengali-origin Muslims primarily occupy these islands, other communities such as Misings, Deoris, Kocharis, Nepalis also live here.
    • In the popular imagination, however, chars have become synonymous to the Bengali-speaking Muslims of dubious nationality.

    Who are the Miyas?

    • The ‘Miya’ community comprises descendants of Muslim migrants from East Bengal (now Bangladesh) to Assam.
    • They came to be referred to as ‘Miyas’, often in a derogatory manner.
    • The community migrated in several waves — starting with the British annexation of Assam in 1826, and continuing into Partition and the 1971 Bangladesh Liberation War.

  • Ladakh Fault in Indus Suture Zone (ISZ)

    A recent survey has found that a tectonic fault line that runs through Ladakh, all along the Indus river, is not inactive as was previously thought and is, in fact, moving northward.

    Tap here to read more about Himalayan orogeny:

    Indus Suture Zone (ISZ)

    • A suture zone is a linear belt of intense deformation, where distinct terranes, or tectonic units with different plate tectonic, metamorphic, and paleogeographic histories, join together.
    • The ISZ represents a belt of tectonic compression caused by the underthrusting of the Indian shield/ plate against the Tibetan mass.
    • It marks the boundary between the Indian and Eurasian plates.
    • The suture zone stretches from the North-Western Himalayan syntaxis bordering the Nanga Parbat to the East as far as the Namche Barwa Mountain.

    Its tectonic activity

    • The Karakoram Range and the Ladakh plateau lie to the north of ISZ and originally formed a part of the European plate.
    • The zone has been neo-tectonically active for the past 78,000-58,000 years.
    • While the frontal and central parts of the Himalayas — the Shivaliks, Himachal Pradesh, Uttarakhand, Jammu and Kashmir and Sikkim — are still known to be active and moving.
    • The fault line runs all along the Indus river, from China through India and Pakistan.
    • The study was conducted in Ladakh from the north of Ladakh’s capital, Leh, to the Tso Moriri lake, a distance of 213 kilometres.

    Why the Ladakh region is more vulnerable?

    • Fault lines weaken the rock formation in the region through which it runs, making the area vulnerable to excessive erosion and landslides.
    • What makes the Ladakh region vulnerable is that unlike other areas in the Himalayas and the rest of the country, there is very little vegetation here and very few trees that can root the soil down.
    • So, in the case of a flash flood or a cloud burst, this can have a widespread impact.

  • Places in news: Kamchatka Peninsula

    An ‘ecological disaster’ of sorts is unfolding on a black volcanic beach of the Kamchatka Peninsula in the Russian Far East, according to a report.

    Note the features of the map and surrounding seas.

    About Kamchatka Peninsula

    • The Kamchatka Peninsula is a 1,250-kilometre-long peninsula in the Russian Far East.
    • The Pacific Ocean and the Sea of Okhotsk make up the peninsula’s eastern and western coastlines, respectively.
    • Immediately offshore along the Pacific coast of the peninsula runs the 10,500-metre-deep Kuril–Kamchatka Trench.
    • The Kamchatka Peninsula, the Commander Islands, and Karaginsky Island constitute the Kamchatka Krai of the Russian Federation.
    • The vast majority of the 322,079 inhabitants are ethnic Russians, although about 13,000 are Koryaks (2014).
    • The Kamchatka peninsula contains the volcanoes of Kamchatka, a UNESCO World Heritage Site.

    Why in news?

    • Then, sea animals begin to die in large numbers, their bodies littering the beach.
    • These included octopuses, seals, sea urchins, stars, crabs and fish.
    • Examination of the seawater by the administration has shown that levels of phenols and oil compounds have spiked.