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Subject: Geography

  • What are Medicanes?

    Very recently, a medicane named Ianos made landfall along the coast of Greece and caused heavy rainfall and flooding on the islands of Zakynthos, Kefalonia and Ithaca.

    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

    What are Medicanes?

    • Medicanes are extra-tropical hurricanes observed over the Mediterranean Sea.
    • Medicanes occur more in colder waters than tropical cyclones, hurricanes and typhoons.
    • Hence, the cores of these storms are also cold, as compared to the warm cores of tropical cyclones.
    • Warmer cores tend to carry more moisture (hence rainfall), are bigger in size and have swifter winds.
    • The main societal hazard posed by Medicanes is not usually from destructive winds but through life-threatening torrential rains and flash floods.

    Why in news?

    • This year is a mild La Niña, according to the World Meteorological Organization.
    • La Niña is the cooling phase of the El Niño Southern Oscillation (ENSO) cycle in the equatorial Pacific Ocean, as opposed to the warming El Niño phase.
    • It is characterized by the unusual cooling of the central and east-central equatorial Pacific Ocean.
    • A La Niña produces more rain in the central-eastern part, where most of the Mediterranean cyclones develop.

  • Re-scaling the height of Mt Everest

    China and Nepal are expected to announce the latest official height of Mt. Everest.

    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

    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 – 8,848m – 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.

    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 measured again?

    • Everest’s current official height– 8,848m– has been widely accepted since 1956, when the figure was measured by the Survey of India.
    • 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.

  • What is the Hangenberg Crisis?

    The explosion of a nearby star — occurred at between Devonian and Carboniferous periods — could have caused a mass extinction event that took place 359 million years ago.

    Try this question from CSP 2018:

    Q.The term “sixth mass extinction/sixth extinction” is often mentioned in the news in the context of the discussion of

    (a) Widespread monoculture Practices agriculture and large-scale commercial farming with indiscriminate use of chemicals in many parts of the world that may result in the loss of good native ecosystems.

    (b) Fears of a possible collision of a meteorite with the Earth in the near future in the manner it happened 65million years ago that caused the mass extinction of many species including those of dinosaurs.

    (c) Large scale cultivation of genetically modified crops in many parts of the world and promoting their cultivationin other Parts of the world which may cause the disappearance of good native crop plants and the loss offood biodiversity.

    (d) Mankind’s over-exploitation/misuse of natural resources, fragmentation/loss, natural habitats, destructionof ecosystems, pollution and global climate change.

    Hangenberg crisis

    • The Earth suffered an intense loss of species diversity that lasted for at least 300,000 years.
    • The event is thought to have been caused by long-lasting ozone depletion, which would have allowed much more of the Sun’s ultraviolet (UV) radiation to reach and harm life on Earth.
    • It was called the Hangenberg crisis.

    What did researchers find?

    • Extensive volcanism and global warming can also rupture the ozone layer but shreds of evidence for these are indefinite as far as the time period is concerned.
    • So, they up that one or more supernovae explosions, at a distance of 65 light-years away from the Earth, may have caused a prolonged loss of ozone.
    • Betelgeuse, a supernova, around 600 light-years away and present outside the kill distance of 25 light-years poses a danger today.
    • Events like gamma-ray bursts, solar eruptions and meteorite collisions end up very soon. As such, they cannot pave the way for gradual ozone depletion that took place at the close of the Devonian aeon.
    • A supernova event can be powerful enough to bathe its galaxy in light for days and months alike. It can be spotted across the universe as well.

    Why Supernovae are considered dangerous?

    • Supernovae (SNe) are quick sources of ionizing photons that include fatal X-rays, UV and gamma rays.
    • Over a longer period of time, the bang clashes with the nearby gas, resulting in a shockwave that causes particle acceleration.
    • As such, cosmic rays are generated by SNe. These charged particles with high energies get magnetically confined on the inside of SN remains.
    • The fossil evidence shows a 300,000-year shrink in biodiversity leading the way to Devonian-Carboniferous Boundary (DCB) mass extinction.
    • This puts forward the possibility of multiple catastrophes or multiple supernovae explosions.

  • Tornado’s dynamics and its India connection

    Babu ChunderSikur Chatterjee’s paper was the earliest record of a tornado’s dynamics in the history of meteorology, according to a study.

    Try this PYQ:

    Q. In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason? (CSP 2015)

    (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

    What is a Tornado?

    • A tornado is a rapidly rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud.
    • The windstorm is often referred to as a twister, whirlwind or cyclone winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern.
    • Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it.
    • It is generally accompanied by extreme weather such as heavy downpours, hail storms, and lightning.

    Who was Babu ChunderSikur Chatterjee?

    • Chatterjee was an Indian scientist employed with the Surveyor General of India during the British colonial era.
    • He was likely the first person to scientifically document a tornado’s path in 1865, a study from the Indian Institute of Tropical Meteorology (IITM), Pune, has claimed.
    • Chatterjee had published his findings in a journal named Proceedings of the Asiatic Society of Bengal, in a paper titled ‘Note on a whirlwind at Pundooah’, near Hooghly.
    • The paper described a tornado’s dynamics in meticulous detail and was accompanied by a sketch that mathematically depicted its scale, track and rotation.

    His work

     

    • Chatterjee quantitatively mapped the entire trail of á tornado’s destruction.
    • He benefited from the rare opportunity to observe a tornado passing through a railway track where there were conveniently placed markers at predefined locations.
    • This enabled him to observe and make clear measurements of the tornado’s direction, dynamics and path.

    Back2Basics

  • [pib] Himalayan Geothermal Springs release huge amount of carbon dioxide in the atmosphere

    The Himalayas, which hosts about 600 geothermal springs needs to be considered while estimating emissions to the carbon cycle and thereby to global warming says, Indian researchers.

    Note the following hot springs in India:

    1) Panamik in Nubra valley

    2) Kheer Ganga in Kullu, Himachal

    3) Manikaran Sahib, Himachal

    4) Tattapani, Chhattisgarh

    5) Gaurikund, Uttarakhand

    6) Yumthang, Sikkim

    7) Reshi, Sikkim

    Geothermal springs

    • Geothermal or Hot springs are heated by shallow intrusions of magma (molten rock) in volcanic areas. Some thermal springs, however, are not related to volcanic activity.
    • The water is heated by convective circulation: groundwater percolates downward & reaches depths of a kilometre or more where the temperature of rocks is high because of the normal temperature gradient of the Earth’s crust.

    Why consider the Himalayas?

    • The Himalayan geothermal springs which cover about 10,000 square km in the Garhwal region of Himalaya show a significant discharge of CO2 rich water.
    • The estimated carbon dioxide degassing (removal of dissolved gases from liquids, especially water or aqueous solutions) flux is nearly 7.2 ×106 mol/year to the atmosphere.
    • Such CO2 degassing should be taken into account to assess global carbon outflux in the earth’s atmosphere.

    Where does this CO2 come from?

    • Carbon outflux from Earth’s interior to the exosphere through volcanic eruptions, fault zones, and geothermal systems contribute to the global carbon cycle that effects short and long term climate of the Earth.
    • The CO2 in the thermal springs are sourced from metamorphic decarbonation of carbonate rocks present deep in the Himalayan core along with magmatism and oxidation of graphite.
    • Most of the geothermal water is dominated by evaporation followed by weathering of silicate rocks.
    • Isotopic analyses further point towards a meteoric source for geothermal water.

  • In news: Mount Sinabung

    The Mount Sinabung volcano in Indonesia has erupted spouting ash at least 5,000 metres high into the sky.

    In the Philippines, a volcano called Taal on the island of Luzon; 50 km from Manila has recently erupted in January. Note all such recent eruption in news.

    Also, try this PYQ:

    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? (CSP 2018)

    (a) 1 only

    (b) 2 and 3 only

    (c) 3 only

    (d) 1 and 3

    Mount Sinabung

    • It is a Pleistocene-to-Holocene stratovolcano in the Karo plateau of Karo Regency, North Sumatra, Indonesia.
    • It is created by the subduction of the Indo-Australian Plate under the Eurasian Plate.
    • It erupted in 2010 after a 400-year-long hiatus and has been continuously active since September 2013.

  • Boreal Summer Intra-Seasonal Oscillation (BSISO)

    Researchers at the Indian National Centre for Ocean Information Services (INCOIS), Hyderabad have reportedly found a way to better forecast the Boreal Summer Intra-Seasonal Oscillation (BSISO).

    Try this PYQ:

    Q.With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct? (CSP 2017)

    1. IOD phenomenon is characterized 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

    What is BSISO?

    • The BSISO of the Asian summer monsoon (ASM) is one of the most prominent sources of short-term climate variability in the global monsoon system.
    • It is the movement of convection (heat) from the Indian Ocean to the western Pacific Ocean roughly every 10-50 days during the monsoon (June-September).
    • Compared with the related Madden-Julian Oscillation (MJO) it is more complex in nature, with prominent northward propagation and variability extending much further from the equator.
    • It represents the monsoon’s ‘active’ and ‘break’ periods, in which weeks of heavy rainfall give way to brilliant sunshine before starting all over again.
    • The active phase also enhances monsoon winds and hence the surface waves.

    Why predict BSISO behaviour?

    • Some phases of boreal summer intraseasonal oscillation or BSISO induce high wave activity in the north Indian Ocean and the Arabian Sea, the researchers claimed.
    • Wave forecast advisories based on the BSISO would be more useful for efficient coastal and marine management.
    • This finding has a great significance in developing seasonal and climate forecast service for waves and coastal erosion for India.

  • In news: Galapagos Islands

    Chinese ships are frequently entering Ecuador’s waters for commercial fishing near the Galapagos Islands.

    Try this question from CSP 2018:

    Q.Which one of the following can one comes across if one travels through the Strait of Malacca?

    (a) Bali

    (b) Brunei

    (c) Java

    (d) Singapore

    The Galapagos Islands

    • Renowned worldwide for its unique species, the islands host a wide array of aquatic wildlife, including marine iguanas, fur seals, and waved albatrosses.
    • The giant tortoises found here – ‘Galápagos’ in old Spanish– give the islands its name.
    • Ecuador made a part of the Galapagos a wildlife sanctuary in 1935, and the sanctuary became the Galapagos National Park in 1959.
    • In 1978, the islands became UNESCO’s first World Heritage Site.
    • It was here that the British naturalist Charles Darwin made key observations in 1835 that shaped his theory of evolution. Darwin described the islands as a “world in itself”.

  • [pib] Tuting-Tidding Suture Zone (TTSZ)

    Earthquake prone zones in India:

  • What is Seismic Noise?

    The seismic noise level has dropped by as much as 50 per cent between March and May due to lockdowns this year, according to researchers.

    Ever heard of space-based monitoring of seismic activities?  This topic creates a scope for potential prelims question…

    What is Seismic Noise?

    • Seismic noise refers to vibrations within the Earth, which are triggered by natural and man-made phenomena like earthquakes, volcanoes and bombs.
    • Seismometers, specialised devices that record ground motions, also capture seismic noise.
    • Everyday human activity — such as road traffic, manufacturing in factories, the sound produced by planes roaring overhead, or simply people walking down the street.
    • The sound signals created by human beings are often referred to as anthropogenic seismic noise.
    • Seismic noise acts almost like background sound for seismologists — it is the unwanted component of signals recorded by a seismometer.

    Variations in noise levels

    • The level of anthropogenic seismic noise recorded varies based on a number of factors.
    • Highly-populated urban areas will generate more vibrations from human activity than less densely populated regions.
    • Timing too plays an important role. The degree of seismic noise is found to be much lower during public holidays.

    Why is this important to record this noise?

    • Due to this, scientists will be able to spot weaker signals.
    • Such small signals tell us about a geological fault making seismic hazard assessment more accurate.
    • This means that scientists will have a better shot at monitoring a whole range of seismogenic behaviour, including the smallest earthquakes or the early signs of a volcanic eruption.