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Subject: Geography

  • ‘Ring of Fire’ Solar Eclipse

    A rare celestial event, an annular solar eclipse popularly called as the ‘ring of fire’ eclipse, will be visible on June 21, 2020 from some parts of Northern India. The first solar eclipse of this year takes place on the summer solstice, which is the longest day in the Northern Hemisphere.

    Try this question from CSP 2019:

    Q. On 21st June, the Sun

    (a) Does not set below the horizon at the Arctic Circle

    (b) Does not set below the horizon at Antarctic Circle

    (c) Shines vertically overhead at noon on the Equator

    (d) Shines vertically overhead at the Tropic of Capricorn

    What is the Solar Eclipse?

    • A Solar Eclipse happens when the moon while orbiting the Earth comes in between the sun and the Earth, due to which the moon blocks the sun’s light from reaching the Earth, causing an eclipse of the sun or a solar eclipse.
    • According to NASA, people who are able to view the total solar eclipse are in the centre of the moon’s shadow as and when it hits the Earth.
    • There are three types of eclipses: one is a total solar eclipse, which is visible only from a small area on Earth. A total solar eclipse happens when the sun, moon and Earth are in a direct line.
    • The second type of a solar eclipse is a partial solar, in which the shadow of the moon appears on a small part of the sun.

    Annular Solar Eclipse

    • The third kind is an annular solar eclipse, which happens when the moon is farthest from the Earth, which is why it seems smaller.
    • In this type of an eclipse, the moon does not block the sun completely, but looks like a “dark disk on top of a larger sun-coloured disk” forming a “ring of fire”.
    • Furthermore, during a solar eclipse, the moon casts two shadows on the Earth; the first one is called the umbra, which gets smaller as it reaches the Earth.
    • The second one is called the penumbra, which gets larger as it reaches the Earth.
    • According to NASA, people standing in the umbra see a total eclipse and those standing in the penumbra see a partial eclipse.

    Why the study of solar eclipse is crucial?

    • One of the reasons that NASA studies solar eclipses is to study the top layer of the sun called the corona.
    • During an annular eclipse, NASA uses ground and space instruments to view this top layer when the sun’s glare is blocked by the moon.

    Back2Basics: Summer Solstice

    • The summer solstice occurs when one of the Earth’s poles has its maximum tilt toward the Sun.
    • It happens twice yearly, once in each hemisphere (Northern and Southern).
    • For that hemisphere, the summer solstice is when the Sun reaches its highest position in the sky and is the day with the longest period of daylight.
    • Within the Arctic circle (for the northern hemisphere) or Antarctic circle (for the southern hemisphere), there is continuous daylight around the summer solstice.
    • On the summer solstice, Earth’s maximum axial tilt toward the Sun is 23.44°. Likewise, the Sun’s declination from the celestial equator is 23.44°.

  • What makes Himalayan tourism spots vulnerable to landslides?

    This newscard talks about the city of Dharamshala where landslides occur frequently.

    Practice question for mains:

    Q.“Himalayan region is more susceptible to floods and flood induced landslides than the Western Ghats”. Discuss.

    Why is Dharamshala more vulnerable to landslides?

    • Dharamshala has a slope varying from gentle to steep, depending on different parts of the city.
    • It is located in Zone V in the earthquake hazard zoning map of India.
    • The large differences in slope between different parts of the city make it more susceptible to critical hazards like landslides.
    • The vulnerability of the geologically young steep slopes of Dhauladhar has increased because of anthropogenic activities and illegal construction due to the lack of availability of land.

    Why do landslides occur?

    • Increasing urbanisation, deforestation and encroachment of areas at high hill slopes, unscientific road cutting and water-intensive agricultural practices contributed to the increase in intensity and frequency of landslides.
    • The situation is worse during the monsoon when landslide-prone areas are washed away due to exposure.
    • This is due to the demand for living within the city. It is not just the difference between slopes, but also anthropogenic causes that lead to the emergence of hazards like landslides.

    Why tourist spots are more vulnerable?

    1) Road traffic is high

    • During the peak tourist season, the road is marred with traffic jams due to continuous sinking.
    • Several factors have continuously contributed to an increase in the road’s vulnerability. The first is Illegal construction and uncontrolled levelling of hillocks along the roads.
    • Hillocks are flattened to accommodate housing projects, commercial establishments, etc. The informal sector often starts residing in these areas which are more vulnerable to risks.
    • These areas have comparatively lower land values and fewer people come to settle here.

    2) Loss in green cover

    • The second is a loss in green cover, something that occurs as more people reside within the city, increasing soil erosion, risking the further vulnerability to landslides.
    • Due to the loss of green cover and steep gradient of the slope, water is not absorbed in the soil and washed away very quickly.

    3) Damaged topography

    • The third is the unscientific manner of cutting hills for widening roads and construction.
    • This causes the sinking of roads, which affects road width and causes traffic interruptions.

    4) Sewage failures

    • The fourth is the absence of a sewerage system in the area. Due to unavailability of sewerage systems, people construct septic tanks that are unsafe for soil strata.
    • Water from septic tanks drains to the upper layer of soil that has loose soil, making areas more vulnerable to damage from landslides.

    Also read

    The Northern and Northeastern Mountains | Part 1

  • I-FLOWS: Mumbai Flood Management System

    Integrated Flood Warning System for Mumbai (I-FLOWS Mumbai), a state-of-the-art flood warning system has been developed for the city.

    Practice question for mains:

    Q. Urban floods in India are consequences of unplanned urbanization in India. Discuss with references to the frequent annual floods in Mumbai.

    What is IFLOWS-Mumbai?

    • IFLOWS is a monitoring and flood warning system that will be able to relay alerts of possible flood-prone areas anywhere between six to 72 hours in advance.
    • The Ministry of Earth Sciences (MoES) has developed the system with in-house expertise and coordination with the Brihanmumbai Municipal Corporation (BMC).
    • The system can provide all information regarding possible flood-prone areas, likely height the floodwater could attain location-wise problem areas across all 24 wards and calculate the vulnerability and risk of elements exposed to flood.
    • Mumbai is only the second city in the country after Chennai to get this system. Similar systems are being developed for Bengaluru and Kolkata.

    How will it work?

    • The primary source for the system is the amount of rainfall, but with Mumbai being a coastal city, the system also factors in tidal waves and storm tides for its flood assessments.
    • The system has provisions to capture the urban drainage within the city and predict the areas of flooding.
    • The system comprises seven modules- Data Assimilation, Flood, Inundation, Vulnerability, Risk, Dissemination Module and Decision Support System.

    Why was this system needed in Mumbai?

    • Mumbai, the financial capital of India, has been experiencing floods with increased periodicity.
    • Floods, especially the ones in 2005 and 2017, are etched in everyone’s memory.
    • Last year, post-monsoon and unseasonal rainfall as late as October, two tropical cyclones in the Arabian Sea had caught authorities off guard and left a trail of destruction.
    • The flood during 26th July 2005, when the city received a rainfall of 94 cm, a 100 year high in a span of 24 hours had paralyzed the city completely.
    • Urban flooding is common in the city from June to September, resulting in the crippling of traffic, railways and airlines.
    • As preparedness for floods before they occur, the system will help in warning the citizens so that they can be prepared in advance for flooding conditions.

    Benefits

    • IFLOWS-Mumbai will enhance the resilience of the city by providing early warning for flooding, especially during high rainfall events and cyclones.
    • Using this, it will be possible to have an estimate of the flood inundation three days in advance, along with immediate weather updates.
    • The Union Minister said the system was “one of the most advanced” ones and will help the city, which has been experiencing floods with increasing periodicity.
    • The hi-tech system will predict floods before they occur, therefore enabling Mumbaikars to take due precautions in advance.

  • Lonar Lake colour changes to pink

    The colour of water in Maharashtra’s Lonar Lake, formed after a meteorite hit the Earth some 50,000 years ago, has changed to glaring.

    Make a note of all saltwater lakes in India. Few of them are Pulicat, Pangong Tso, Chilika, and Sambhar Lakes etc.

    About Lonar Lake

    • Lonar Lake, also known as Lonar crater, is a notified National Geo-heritage Monument, saline (pH of 10.5), Soda Lake, located at Lonar in Buldhana district, Maharashtra.
    • It was created by an asteroid collision with earth impact during the Pleistocene Epoch.
    • It is one of the four known, hyper-velocity, impact craters in basaltic rock anywhere on Earth.
    • It sits inside the Deccan Plateau—a massive plain of volcanic basalt rock created by eruptions some 65 million years ago.
    • Its location in this basalt field suggested to some geologists that it was a volcanic crater.

    Why there’s a color change?

    • The salinity and algae can be responsible for this change.
    • There is no oxygen below one meter of the lake’s water surface.
    • There is an example of a lake in Iran, where water becomes reddish due to increase in salinity.
    • The level of water in the Lonar Lake is currently low as compared to the few past years and there is no rain to pour fresh water in it.
    • The low level of water may lead to increased salinity and change in the behaviour of algae because of atmospheric changes.

  • Challenger Deep: the deepest spot in the ocean

    On June 7, astronaut and oceanographer Kathy Sullivan, who was the first American woman to walk in space in 1984, became the first woman and the fifth person in history to descend to the deepest known spot in the world’s oceans, called the Challenger Deep in the Mariana Trench.

    The ocean relief can be divided into various parts such as Continental Shelf, Continental Slope, Continental Rise or Foot, Deep Ocean basins, Abyssal plains & Abyssal Hills, Oceanic Trenches, Seamounts and Guyots.

    Revise these ocean bottom relief  features from your basic references.

    Also revise India’s Deep Ocean Mission.

    What is Challenger Deep?

    • The Challenger Deep is the deepest known point in the Earth’s seabed hydrosphere (the oceans), with a depth of 10,902 to 10,929 m.
    • The deepest part is called the Challenger Deep, which is located below the surface of the western Pacific Ocean.
    • The first dive at Challenger Deep was made in 1960 by Lieutenant Don Walsh and Swiss scientist Jacques Piccard on a submersible called ‘Trieste’.
    • The British Ship HMS Challenger discovered Challenger Deep between 1872-1876.
    • In 2012, film director James Cameron reached the bottom of the Mariana trench after a descent that lasted 2 hours and 36 minutes.
    • Cameron reached a depth of about 10,908 metres on a dive in his submersible called the ‘Deepsea Challenger’ and became the first to complete a solo submarine dive to this spot.

    Why explore deep oceans?

    • Ocean exploration, however, is not randomly wandering in hopes of finding something new.
    • It is disciplined and organized and includes rigorous observations and documentation of biological, chemical, physical, geological, and archaeological aspects of the ocean.
    • Most of the existing knowledge of the oceans comes from shallower waters, while deeper waters remain relatively unexplored, even as humans are relying more on these areas for food, energy and other resources.
    • Further, finding out more about the deep ocean areas can potentially reveal new sources for medical drugs, food, energy resources and other products.
    • Significantly, information from the deep oceans can also help to predict earthquakes and tsunamis, and help us understand how we are affecting and getting affected by the Earth’s environment.

    What does it take to reach the deep ocean?

    • Vehicles called Human Occupied Vehicles (HOVs) may be used that carry scientists to the deep sea.
    • Alternatively, there are unmanned Remotely Operated Vehicles (ROVs) that are linked to ships using cables and can be steered by scientists remotely.
    • Even so, it is difficult for most private citizens to travel more than 100 feet below the surface of the ocean.
    • Further, technical divers can go as deep as 500 feet or more, but with an array of tanks filled with different gas blends.

    Why is it so difficult to explore deep oceans?

    • Most recreational divers can’t explore more than about 120 feet down due to the amount of air needed to keep lungs pressurized at depth.
    • Such depths could lead to nitrogen narcosis, the intoxication by nitrogen that starts to set in around that depth (most of our atmosphere is nitrogen, not oxygen).
    • Waters at such depths of several kilometres exert tremendous pressure which human bodies cannot sustain.

  • Permafrost and the hazards of its Thawing

    The principal reason that led to the recent 20,000-tonne oil leak at an Arctic region power plant in Russia that is now being recognised is the sinking of ground surface due to permafrost thaw.

    Try this question from Mains 2017:
    Q. What is Cryosphere? How does the Cryosphere affect global climate?

    What is Permafrost?

    • Permafrost is ground that remains completely frozen at 0 degrees Celsius or below for at least two years.
    • It is defined solely based on temperature and duration.
    • The permanently frozen ground, consisting of soil, sand, and rock held together by ice, is believed to have formed during glacial periods dating several millennia.

    Where are they found?

    • These grounds are known to be below 22 per cent of the land surface on Earth, mostly in polar zones and regions with high mountains.
    • They are spread across 55 per cent of the landmass in Russia and Canada, 85 per cent in the US state of Alaska, and possibly the entirety of Antarctica.
    • In northern Siberia, it forms a layer that is 1,500 m thick; 740 m in northern Alaska.
    • At lower latitudes, permafrost is found at high altitude locations such as the Alps and the Tibetian plateau.

    How climate change is eating away at these grounds?

    • The Earth’s polar and high altitude regions — its principal permafrost reservoirs — are the most threatened by climate change.
    • Arctic regions are warming twice as fast compared to the rest of the planet, its current rate of temperature change being the highest in 2,000 years.
    • In 2016, Arctic permafrost temperatures were 3.5 degrees Celsius higher than at the beginning of the 20th century.
    • A study has shown that every 1 degree Celsius rise in temperature can degrade up to 39 lakh square kilometre due to thawing.
    • This degradation is expected to further aggravate as the climate gets warmer, putting at risk 40 per cent of the world’s permafrost towards the end of the century– causing disastrous effects.

    The threat to infrastructure

    • Thawing permafrost is also ominous for man-made structures overhead.
    • The Russian oil leak occurred recorded temperatures in Siberia at more than 10 degrees Celsius above average, and called them “highly anomalous” for the region where the power plant is located.
    • As temperatures rise, the binding ice in permafrost melts, making the ground unstable and leading to massive potholes, landslides, and floods.
    • The sinking effect causes damage to key infrastructure such as roads, railway lines, buildings, power lines and pipelines.
    • These changes also threaten the survival of indigenous people, as well as Arctic animals.

    A ticking time bomb

    • Beneath its surface, permafrost contains large quantities of organic leftover from thousands of years prior — dead remains of plants, animals, and microorganisms that got frozen before they could rot.
    • It also holds a massive trove of pathogens.
    • When permafrost thaws, microbes start decomposing this carbon matter, releasing greenhouse gases like methane and carbon dioxide.
    • Researchers have estimated that for every 1 degree Celsius rise in temperature, these grounds could release GHGs to the tune of 4-6 years’ of emissions from coal, oil, and natural gas.
    • Along with greenhouse houses, these grounds could also release ancient bacteria and viruses into the atmosphere as they unfreeze.

    Back2Basics
    https://www.civilsdaily.com/news/thawing-of-permafrost/

    Also read:

    Ambarnaya River Oil spill in Russia

  • What is Lunar Eclipse?

    A penumbral lunar eclipse will be observed today midnight. The Earth will imperfectly align itself between the Sun and the moon, casting a shadow on the latter, marking the second lunar eclipse of the year.

    Solar and Lunar eclipse has been quite frequent this year. Mark the major differences between them.

    Lunar Eclipse

    • A lunar eclipse occurs when the Moon moves into the Earth’s shadow.
    • This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned with Earth between the other two.
    • A lunar eclipse can occur only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon’s proximity to either node of its orbit.
    • Any object that obstructs light will produce two shadows: one which will be dark and dense, is called the umbra; and the other which is light and diffused is called the penumbra.
    • The only light reflected from the lunar surface has been refracted by Earth’s atmosphere.
    • This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light. Due to this reddish colour, a totally eclipsed Moon is sometimes called a blood moon.

    Types

    • In a total eclipse of the moon, the inner part of Earth’s shadow, called the umbra, falls on the moon’s face. At mid-eclipse, the entire moon is in shadow, which may appear blood red.
    • In a partial lunar eclipse, the umbra takes a bite out of only a fraction of the moon. The dark bite grows larger and then recedes, never reaching the total phase.
    • In a penumbral lunar eclipse, only the more diffuse outer shadow of Earth – the penumbra – falls on the moon’s face. This third kind of lunar eclipse is much more subtle and much more difficult to observe than either a total or partial eclipse of the moon.

    How it is different from Solar Eclipse?

    • A solar eclipse happens when the moon passes in between the earth and the sun. A lunar eclipse happens when the earth passes in between the moon and the sun.
    • During a solar eclipse, the moon partially or fully hides the sun’s rays for a few minutes.
    • Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth.
    • Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.

    What’s special this time?

    • This eclipse is also called a strawberry moon eclipse — the term, interestingly, originates from an American concept and has little to do with the Euro-Asia region.
    • June’s full moon usually coincides with the harvesting season of wild strawberries in America and the phenomenon was often addressed in reference to that.
    • India had already witnessed an eclipse earlier this year, in January.
    • The strawberry moon eclipse is going to be its second and probably the last visible lunar one in 2020.

  • Ambarnaya River Oil spill in Russia

    Russia has declared a state of emergency after a power plant fuel leak in its Arctic region caused 20,000 tonnes of diesel oil to escape into a local river, turning its surface crimson red.

    Locate major rivers in Russia in the given map from east-west and west-east directions.

    Details of the spillage

    • The Ambarnaya River, into which the oil has been discharged, is part of a network that flows into the environmentally sensitive Arctic Ocean.
    • The state-owned TASS news agency reported that the emergency measures were announced within Russia’s Krasnoyarsk Region, located in the vast and sparsely populated Siberian peninsula.

    How did the leak happen?

    • The thermoelectric power plant at Norilsk is built on permafrost, which has weakened over the years owing to climate change.
    • The power plant is located near the Region’s Norilsk city, around 3000 km northeast of Moscow.
    • This caused the pillars that supported the plant’s fuel tank to sink.
    • Around 20,000 tonnes of diesel oil was released into the Ambarnaya river, which has since drifted 12 km on its surface.

    What has Russia done so far?

    • Boom obstacles were placed in the river, but they were unable to contain the oil because of shallow waters.
    • The state of emergency declared would bring in extra forces and federal resources for the clean-up efforts.

    What is the extent of the damage?

    • Environmentalists have said the river would be difficult to clean, given its shallow waters and remote location, as well as the magnitude of the spill.
    • This is the second-largest known oil leak in modern Russia’s history in terms of volume.
    • The clean-up effort could take between 5-10 years.

  • Extreme weather events in India

    Nineteen extreme weather events in 2019 claimed 1,357 lives, with heavy rain and flood accounting for 63 per cent of these deaths, revealed Down To Earth’s State of India’s Environment 2020 report.

    Extreme weather events:

    • Extreme weather events are out of the ordinary, unexpected, unusual climatic events which wreak havoc and disrupt everyday life.
    • Over the years, the frequency of extreme weather events has increased due to global warming and climate change.
    • Extreme weather events include hailstorm, heatwaves, dust storm, cloud bursts etc.

    Try this question:

    Q. Extreme weather events have been the biggest catastrophe in India this year. Discuss.

    Data from this newscard can be used to substantiate your mains answer with relevant data.

    Loss of lives

    • The most lives were lost in Bihar, with people dying from floods and heavy rain (306), thunderstorms (71) and heatwave (292) between May and October.
    • In Maharashtra, 136 people died from floods and heavy rain, 51 died from lightning and 44 died from the heatwave between June and September.
    • There was a 69 per cent increase in the number of heatwave days between 2013 and 2019 as well, the report said.
    • Over 5,300 people died from heatwaves in the past seven years.
    • Cold waves increased by 69 per cent within a year, between 2017 and 2018, with the latter year reported having an extremely cold winter, with the most casualties (279) in the past seven years.

    Risks of Extreme weather events in India

    • Climate change related risks will increasingly affect the Indian subcontinent, including via sea level rise, cyclonic activity and changes in temperature and precipitation patterns.
    • Rising sea levels would submerge low-lying islands and coastal lands and contaminate coastal freshwater reserves.Climate change will increase the risks of death, injury and ill-health and disrupt livelihoods in low-lying coastal zones due to cyclones and coastal and inland flooding, storm surges and sea-level rise.
    • Melting Himalayan glaciers would reduce downstream water supply in many of India’s important rivers in the dry season, impacting millions
    • A warmer atmosphere will spread tropical diseases and pests to new areas.
    • Increased river, coastal and urban floods could cause considerable loss of life and widespread damage to property, infrastructure and settlements.
    • Erratic rainfall in parts of India could lower rice yields and lead to higher food prices and living costs, while increased drought related water and food shortages linked to rising and extreme temperatures may increase malnutrition and worsen rural poverty. Over 55% of Indian rural households depend on agriculture for a living and, with fisheries and forestry,

    Systems in place to tackle extreme weather events are as follows:

    1.Meteorological predictions

    2.Contingency fund

    3.Early warning to citizens

    4.NDMA has issued an action plan for Prevention and Management of Heat Waves.

    5.Remote sensing satellites.

    Problems with accurate meteorological predictions are as follows:

    1.Meteorological predictions are considered for broad geographical areas and timeframes. It is not yet possible to predict a thunderstorm or lightning at a village or a part of a city.

    2.The exact times these events will hit, too, cannot be predicted.

    3.Alerts and warnings are in the nature of a general advisory, telling the people to expect these events, and to take precautions

    Steps taken by the State government are as follows:

    1.Rajasthan:

    • storm has been included in the category of natural disasters for the first time in the State and funds to the tune of ₹2.55 crore have been sanctioned to the affected districts.
    • The next of kin of each deceased in Rajasthan will get financial assistance of ₹4 lakh from the Chief Minister’s Relief Fund.
    • Power discoms have launched action on a war-footing to restore electricity supply in the affected areas, while the administration has ordered a survey of damaged properties.
    • In Dholpur district, relief camps have been opened for the villagers whose houses were destroyed.

    2.Uttar Pradesh:

    • The Uttar Pradesh Chief Minister has announced a compensation of up to Rs 400,000 to the families of the deceased and Rs 50,000 for each of the injured in the heavy rainfall and storm across the state.
    • contingency funds have been released to the respective district administration.

  • Heatwaves and its unusualness this year

    For the past five days, Rajasthan, Delhi, Uttar Pradesh, Madhya Pradesh, and Maharashtra have been experiencing severe to very severe heatwave conditions. Here is why this summer is slightly unusual.

    Heatwaves being more frequent phenomena, the UPSC may end up asking a prelim as well as mains question about it.  It may ask Q. What are heat waves and how are they classified? What are the external factors on which it is depended?

    A MCQ may be a statement based question mentioning the criteria for declaring a heatwave.

    What is a heatwave and when is it declared?

    Heatwaves occur over India between March and June.

    • IMD declares a heatwave event when the maximum (day) temperature for a location in the plains crosses 40 degrees Celsius.
    • Over the hills, the threshold temperature is 30 degrees Celsius.

    Following criteria are used to declare heatwave:

    To declare heatwave, the below criteria should be met at least in 2 stations in a Meteorological subdivision for at least two consecutive days and it will be declared on the second day.

    a) Based on Departure from Normal

    • Heat Wave: Departure from normal is 4.5°C to 6.4°C
    • Severe Heat Wave: Departure from normal is >6.4°C

    b) Based on Actual Maximum Temperature (for plains only)

    • Heat Wave: When actual maximum temperature ≥ 45°C
    • Severe Heat Wave: When actual maximum temperature ≥47°C

    How long can a heatwave spell last?

    • A heatwave spell generally lasts for a minimum of four days. On some occasions, it can extend up to seven or ten days.
    • The longest recorded heatwave spell, in recent years, was between 18 – 31 May 2015.
    • This spell had severely affected parts of West Bengal along with Odisha, Andhra Pradesh, and Telangana.
    • Heatwave conditions occurring in May have been observed to last longer, as the season reaches its peak this month.
    • Whereas those reported in June often die down sooner, often due to the onset of Southwest monsoon over the location or in its neighbourhood.

    Does all of India experience heatwave conditions?

    • Heatwaves are common over the Core Heatwave Zone (CHZ) — Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Orissa, Vidarbha in Maharashtra.
    • The CHZ also includes parts of Gangetic West Bengal, Coastal Andhra Pradesh and Telangana, as categorised by IMD.
    • Several recent studies indicate that CHZ experience more than six heatwave days per year during these four months.
    • Many places in the northwest and cities along southeastern coast report eight heatwave days per season.
    • However, the regions in the extreme north, northeast and southwestern India are lesser prone to heatwaves.

    Whats’ so unusual this year?

    • Summer season reaches its peak by May 15 in India when the day temperatures across north, west, and central India cross 40 degrees and hover close to 45 degrees then on.
    • This year, north India did not experience such temperatures till May 21.
    • It was mainly because of the continuous inflow of Western Disturbances that influenced the weather in the north till as late as April.
    • Since last winter, there was frequent passing of Western Disturbances over the north, appearing after every five to seven days.

    What are these Western Disturbances?

    • Originating in the Mediterranean Sea, Western Disturbances are eastward-moving winds that blow in lower atmospheric levels.
    • They affect the local weather of a region during its onward journey.
    • Between January and March this year, there were about 20 Western Disturbances, a record of sorts.
    • When Western Disturbances interact with weather systems heading from the two southern seas, that is, warm winds blowing in from the Bay of Bengal or the Arabian Sea, they cause snowfall or rainfall over the north.
    • A significant influence of Western Disturbances is experienced from December to February. However, this year, its influence persisted until early May.
    • The recent Western Disturbances got support from easterly winds blowing over from the Bay of Bengal.

    Has cyclone Amphan influenced the current heatwave?

    • Since the event of severe heat has emerged immediately after the passing of Cyclone Amphan, experts confirm its role in leading to the present heatwave spell.
    • Cyclone Amphan, which was a massive Super Storm covering 700 km, managed to drag maximum moisture from over the Bay of Bengal to entire Peninsula.
    • All the moisture that was otherwise built during the thunderstorm and rainfall got gradually depleted from over vast areas as the storm advanced towards West Bengal and Bangladesh between May 16 and 20.
    • It has now triggered dry north-westerly winds to blow over Rajasthan, Madhya Pradesh, Uttar Pradesh and Maharashtra causing severe heatwave.