Category: World Geography

Heat Waves

Why in News?

  • The India Meteorological Department (IMD) warned heatwaves for more than 8 states recently.

What is a heatwave?

  • A region is considered to be under the grip of a heatwave if the maximum temperature reaches at least 40 degrees Celsius or more in the plains and at least 30 degrees Celsius or more in hilly regions.
  • When the maximum temperature departure ranges between 4.5 and 6 degrees, the India Meteorological Department (IMD) declares a heatwave.
  • A severe heatwave is declared when the recorded maximum temperature of a locality departure from normal is over 6.4 degrees Celsius.
  • Also, if an area records over 45 degrees and 47 degrees Celsius on any given day, then the IMD declares heatwave and severe heatwave conditions, respectively.

Reasons:

  • The lack of pre-monsoon showers has also led to an increase in the overall maximum temperature. Maharashtra recorded 63 per cent deficient rainfall from March 1 to April 26.
  • Reasons why overall India is experiencing more heat waves are:
  • Magnified effect of paved and concrete surfaces in urban areas and a lack of tree cover.
  • Urban heat island effects can make ambient temperatures feel 3 to 4 degrees more than what they are.More heat waves were expected as globally temperatures had risen by an average 0.8 degrees in the past 100 years. Night-time temperatures are rising too.
  • Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.
  • High intensity of UV rays in medium-high heat wave zones.
  • Combination of exceptional heat stress and a predominantly rural population makes India vulnerable to heat waves.

Way ahead for India- How should India deal with heat waves?

  • Identifying heat hot-spots through appropriate tracking of meteorological data and promoting timely development and implementation of local Heat Action Plans with strategic inter-agency co-ordination, and a response which targets the most vulnerable groups.
  • Review of existing occupational health standards, labour laws and sectoral regulations for worker safety in relation to climatic conditions.
  • Policy intervention and coordination across three sectors health, water and power is necessary.Promotion of traditional adaptation practices, such as staying indoors and wearing comfortable clothes.
  • Popularisation of simple design features such as shaded windows, underground water storage tanks and insulating housing materials.
  • Advance implementation of local Heat Action Plans, plus effective inter-agency coordination is a vital response which the government can deploy in order to protect vulnerable groups.

The most heatwave prone areas — known as the Core Heatwave Zone (CHZ) are:

  • Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Orissa, Vidarbha in Maharashtra, parts of Gangetic West Bengal, Coastal Andhra Pradesh, and Telangana.

El – Nino

Why in News?

  • A record three-year La Nina event ended in March 2023 and currently, the equatorial Pacific Ocean is at normal temperatures, known as the neutral phase.

What is El Nino?

  • El Nino was first recognized by Peruvian fishermen off the coast of Peru as the appearance of unusually warm water.
  • The Spanish immigrants called it El Nino, meaning “the little boy” in Spanish.
  • The El Nino is the warmer-than-normal phase of the El Nino Southern Oscillation (ENSO) phenomenon, during which there are generally warmer temperatures and less rainfall than normal in many regions of the world, including India.
  • During an El Nino event, the Sea Surface Temperatures (SST) in the equatorial Pacific Ocean off the northern coast of South America became at least 0.5 degrees Celsius warmer than the long-term average.
  • In the case of a strong El Nino event as occurred in 2015-2016, anomalies can reach as high as 3°C, which is a record.
  • The El Nino event is not a regular cycle, they are not predictable and occur irregularly at two- to seven-year intervals.
  • Climatologists determined that El Nino occurs simultaneously with the Southern Oscillation.
  • The Southern Oscillation is a change in air pressure over the tropical Pacific Ocean.

Impact on India:

  • Weak Monsoon for India: The development of an El Nino in May or June 2023 may cause weakening of the southwest monsoon season, which brings around 70% of the total rainfall India receives and on which most of its farmers still depend.
  • However, sub-seasonal factors such as the Madden-Julian Oscillation (MJO) and monsoon low-pressure systems can temporarily enhance rainfall in some parts as witnessed in the year 2015.
  • Hot Temperatures: It may also cause heatwaves and droughts in India and other regions around the world such as South Africa, Australia, Indonesia and the Pacific Islands.
  • Heavier Rainfall in the West: It brings heavy rainfall and flooding to other regions such as California in the United States and could cause bleaching and death of coral reefs.
  • Rising Global Average Temp: The El Nino in 2023 and going into 2024 may push the global average temperature towards 1.5°C warmer than the preindustrial average.
  • The warming of the oceans is also one of the major impacts of an El Nino event.
  • This is when ocean heat content is already at a record high, according to the World Meteorological Organization (WMO).

Previous Such Occurrences – Impacts:

  • In the 2015-2016, there were widespread heatwaves in India that killed around 2,500 people in each of the years.Coral reefs around the world also suffered from bleaching and the sea level rose by 7 millimetres due to thermal expansion.
  • The El Nino, along with global warming, had made 2016 the warmest year on record.
  • El Nino events of 1982-83 and 1997-98 were the most intense of the 20th century.
  • During the 1982-83 event, sea surface temperatures in the eastern tropical Pacific were 9-18°C above normal.

What is MJO?

  • The MJO is made up of two parts: an enhanced rainfall phase and a suppressed rainfall phase.
  • During the enhanced phase, surface winds converge, causing air to rise and create more rainfall. In the suppressed phase, winds converge at the top of the atmosphere, causing air to sink and leading to less rainfall.
  • This dipole structure moves west to east in the Tropics, creating more cloudiness and rainfall in the enhanced phase, and more sunshine and dryness in the suppressed phase.

How does ENSO Affect India?

  • The influence of ENSO on India’s climate is most pronounced during the monsoon season. During an El Niño event, India experiences below-average rainfall.
  • The El Niño also leads to a rise in temperatures, exacerbating heat waves and causing heat-related health issues.
  • On the other hand, during a La Niña event, India experiences above-average rainfall.
  • This can lead to flooding and landslides, damaging crops and infrastructure. However, La Niña also brings cooler temperatures, which can provide relief from heat waves.

Odisha reports 542 forest fires in last 7 days, highest in India

Why in News?

  • Forest fires continued to remain unabated in Odisha after the state recorded 542 such cases in the last seven days making it the highest among all states in the country.

What is Wildfire?

  • Also called forest, bush or vegetation fire, can be described as any uncontrolled and non-prescribed combustion or burning of plants in a natural setting such as a forest, grassland, brush land or tundra, which consumes the natural fuels and spreads based on environmental conditions (e.g., wind, topography).
  • Wildfires can be incited by human actions, such as land clearing, extreme drought or in rare cases by lightning.
  • There are three conditions that need to be present in order for a wildfire to burn: fuel, oxygen, and a heat source.

Human-induced Climate Change:

  • Increases in greenhouse gases resulting from human activities have led to a net effect of warming of the climate system leading to direct impacts including increased air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.
  • The increases in greenhouse gases can be attributed to fossil fuel use, land-use change, etc.

Types of a forest fire:

  • Surface fire: Spread along the surface litter (leaves, twigs, dry grasses) on the forest floor.
  • Ground fire: Fires in the subsurface organic fuels, such as duff layers under forest stands, burn underneath and are often ignited by surface fires.
  • Crown fire: A crown fire is one in which the crown of trees and shrubs burn, often sustained by a surface fire.

Factors causing Forestfire:

  • Climate change increases the frequency and severity of fire weather around the world.
  • Increased fire weather from climate change amplifies fire risk where fuels remain available.
  • Fire weather is a combination of conditions that set the stage for the rapid spread of wildfires.
  • High temperature
  • Low Relative humidity
  • Strong sustained winds (> 20 mph) carry oxygen and spread flames.
  • Poor land and forest management also contributes to the wildfires, however, it does not alone account for the recent increases in the extent and severity of the wildfires globally.
  • Factors Identified by the IPCC: The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), published in 2013, identified a few factors that could influence the way wildfires play out. These include:
  • Global increase in average temperatures.
  • Global increases in the frequency, intensity and extent of heatwaves (breaching of historically extreme temperature thresholds).
  • Regional increases in the frequency, duration and intensity of droughts.

Concerns:

  • Forest fires have become an issue of global concern. In many countries, wildfires are burning larger areas, and fire seasons are growing longer due to global warming.
  • Australia previously battled its largest bushfire on record, while parts of the Arctic, the Amazon and central Asia have also experienced unusually severe fires.
  • Wildfires in Western USA (California) are another example.
  • Globally, forest fires release billions of tons of CO2 into the atmosphere, while hundreds of thousands of people are believed to die due to illnesses caused by exposure to smoke from forest fires and other landscape fires.

Heat Waves

Why in News?

  • The India Meteorological Department (IMD) warned that the maximum temperatures over northwest, west, and central India would be 3-5° C higher than the long-term average.

What is a heatwave?

  • A region is considered to be under the grip of a heatwave if the maximum temperature reaches at least 40 degrees Celsius or more in the plains and at least 30 degrees Celsius or more in hilly regions.
  • When the maximum temperature departure ranges between 4.5 and 6 degrees, the India Meteorological Department (IMD) declares a heatwave.
  • A severe heatwave is declared when the recorded maximum temperature of a locality departure from normal is over 6.4 degrees Celsius.
  • Also, if an area records over 45 degrees and 47 degrees Celsius on any given day, then the IMD declares heatwave and severe heatwave conditions, respectively.

Reasons:

  • The lack of pre-monsoon showers has also led to an increase in the overall maximum temperature. Maharashtra recorded 63 per cent deficient rainfall from March 1 to April 26.
  • Reasons why overall India is experiencing more heat waves are:
  • Magnified effect of paved and concrete surfaces in urban areas and a lack of tree cover.
  • Urban heat island effects can make ambient temperatures feel 3 to 4 degrees more than what they are.
  • More heat waves were expected as globally temperatures had risen by an average 0.8 degrees in the past 100 years. Night-time temperatures are rising too.
  • Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.
  • High intensity of UV rays in medium-high heat wave zones.
  • Combination of exceptional heat stress and a predominantly rural population makes India vulnerable to heat waves.

Way ahead for India- How should India deal with heat waves?

  • Identifying heat hot-spots through appropriate tracking of meteorological data and promoting timely development and implementation of local Heat Action Plans with strategic inter-agency co-ordination, and a response which targets the most vulnerable groups.Review of existing occupational health standards, labour laws and sectoral regulations for worker safety in relation to climatic conditions.
  • Policy intervention and coordination across three sectors health, water and power is necessary.Promotion of traditional adaptation practices, such as staying indoors and wearing comfortable clothes.
  • Popularisation of simple design features such as shaded windows, underground water storage tanks and insulating housing materials.
  • Advance implementation of local Heat Action Plans, plus effective inter-agency coordination is a vital response which the government can deploy in order to protect vulnerable groups.

The most heatwave prone areas — known as the Core Heatwave Zone (CHZ) are:

  • Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Orissa, Vidarbha in Maharashtra, parts of Gangetic West Bengal, Coastal Andhra Pradesh, and Telangana.

Sinking of Joshimath in Uttarakhand

Why in News?

  • The Uttarakhand government has banned construction work in and around Joshimath due to land subsidence, which has resulted in cracks in over 560 homes, prompting panicked locals to protest.

Science behind the subsidence: 

  • Location, topography: Also known as Jyotirmath, it is a town (of over 20,000 population) in the Garhwal Himalayas in Chamoli District in Uttarakhand, located on the NH-7 (Rishikesh-Badrinath) at an altitude of 1890
  • It is situated in the middle slopes of a hill bounded by the Karmanasa and Dhaknala streams on the west and the east and the Dhauliganga and Alaknanda rivers on the south and the north.
  • According to the Mishra Commission report (1976), the first instance of subsidence in Joshimath was reported way back in 1976 and the town is –
  • Located on the site of ancient landslides
  • Covered with thick layer of overburden material
  • The town area is prone to landslides and highly vulnerable to sinking due to scattered and highly weathered gneissic rocks with a low bearing capacity and loose soil due to seepage from streams uphill.

Extreme weather events:

  • Flood events of June 2013 and February 2021 (flooding of Rishi Ganga) had adverse impact on the landslide zone as a result of extreme erosion.
  • According to the latest satellite data, mountain streams have expanded their channels and changed course, thereby inducing more slope instability in an already fragile belt.

Geology:

  • According to the Uttarakhand State Disaster Management Authority (USDMA), Joshimath falls in Zone V of the Seismic Zonation Map and has witnessed several earthquakes of magnitude of less than 5 on the Richter scale.
  • Joshimath being on a fault line makes it highly vulnerable to sinking because of tectonic activity.

Unplanned construction:

  • The Border Roads Organisation (BRO) is building the Helang bypass that will reduce the distance to Badrinath shrine by about 30 km, using heavy machinery.
  • Hydroelectric (HE) schemes have been sanctioned around Joshimath and Tapovan, including the Vishnugad HE Project and a tunnel boring machine (TBM) was employed for excavating the tunnel for the project.
  • In 2009, it punctured a water-bearing strata and experts had warned that this sudden and large-scale dewatering of the strata had the potential of initiating ground subsidence in the region.
  • Improper water drainage: According to the USDMA, this could be the reason for increase in ground seepage of water from the surface, which is a probable cause for subsidence.

Preventive measures:

  • Immediate Measures:
  • Relocating residents to a safer place.
  • Experts recommend that all development and hydroelectric projects in the region be halted completely.
  • Long – Term Measures:
  • The town’s planning must be reimagined to accommodate the new variables and changing geographical factors.
  • One of the most important factors that needs to be studied and redeveloped is drainage and sewer planning.
  • Experts have also suggested replanting in the region, particularly in vulnerable areas, to retain soil capacity.

Way Forward:

  •  To save Joshimath, the government and civil bodies must work together, with the assistance of military organisations such as the Border Roads Organisation (BRO).

Cyclone Mandous

Why in News?

  • With the cyclonic storm ‘Mandous’, brewing over the Bay of Bengal, likely to hit north Tamil Nadu and Puducherry coasts.

What are Tropical Cyclones?

  • Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large-scale destruction caused by violent winds, very heavy rainfall and storm surges.
  • Tropical Cyclones are one of the most devastating natural calamities in the world.
  • Tropical cyclones originate and intensify over warm tropical oceans. 

Favourable Conditions for formation:

  • Large sea surface with temperature higher than 27° C.
  • Presence of the Coriolis force.
  • Small variations in the vertical wind speed.
  • A pre-existing weak low- pressure area or low-level-cyclonic circulation.
  • Upper divergence above the sea level system.

Stages of Formation of Tropical Cyclones:

  • The development cycle of tropical cyclones may be divided into three stages:
  • Formation and Initial Development Stage
  • The formation and initial development of a cyclonic storm depends upon the transfer of water vapour and heat from the warm ocean to the overlying air, primarily by evaporation from the sea surface.
  • It encourages formation of massive vertical cumulus clouds due to convection with condensation of rising air above the ocean surface.
  • Mature Stage:
  • When a tropical storm intensifies, the air rises in vigorous thunderstorms and tends to spread out horizontally at the tropopause level. Once air spreads out, a positive pressure at high levels is produced, which accelerates the downward motion of air due to convection.
  • With the inducement of subsidence, air warms up by compression and a warm ‘Eye’ (Low pressure centre) is generated. The main physical feature of a mature tropical cyclone in the Indian Ocean is a concentric pattern of highly turbulent giant cumulus thundercloud bands.
  • Modification and Decay:
  • A tropical cyclone begins to weaken in terms of its central low pressure, internal warmth and extremely high speeds, as soon as its source of warm moist air begins to ebb or is abruptly cut off.
  • This happens after its landfall or when it passes over cold waters.

Cyclones in India:

  • Tropical cyclones originate over the Bay of Bengal, Arabian Sea and the Indian Ocean. These tropical cyclones have very high wind velocity and heavy rainfall and hit the Indian Coastal states of Tamil Nadu, Andhra Pradesh, West Bengal, Odisha and Gujarat (These five states are more vulnerable to cyclone disasters than others in India).
  • Most of these cyclones are very destructive due to high wind velocity and torrential rain that accompanies it.
  • There are three elements associated with cyclones which cause destruction during its occurrence. These are-
  • Strong Winds/Squall: It damages installations, dwellings, communications systems, trees etc., resulting in loss of life and property.
  • Torrential rains and inland flooding: Rain is a serious problem for the people who become shelter less due to the cyclone. Heavy rainfall is usually spread over a wide area and causes large scale soil erosion and weakening of embankments.
  • Storm Surge: It is an abnormal rise of sea level near the coast caused by a severe tropical cyclone. Due to storm Surge Sea water inundates low lying areas of coastal regions drowning human beings and livestock, causes eroding beaches and embankments, destroys vegetation and leads to reduction of soil fertility.

Management of Cyclones:

  • There are many structural and non-structural measures for effective disaster management of cyclones.
  • The structural measures include construction of cyclone shelters, construction of cyclone resistant buildings, road links, culverts, bridges, canals, drains, saline embankments, surface water tanks, communication and power transmission networks etc.
  • Non-structural measures like early warning dissemination systems, management of coastal zones, awareness generation and disaster risk management and capacity building of all the stakeholders involved.
  • These measures are being adopted and tackled on a State to State basis under the National Cyclone Risk Mitigation Project (NCRMP) being implemented through World Bank Assistance.

Tonga Volcanic Eruption

Why in News?

  • Tonga Eruption Seabed Mapping Project (TESMaP) has said that the eruption of the Hunga-Tonga-Hunga-Ha’apai volcano on 15 January 2022 was the largest recorded since the eruption of Krakatoa in 1883 (Indonesia).

About the News:

  • It is an Undersea Volcanic Eruption consisting of two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga.
  • The Tonga Islands occur along the Ring of Fire—a perimeter of heightened volcanic and seismic activity that encircles the Pacific Ocean basin.

Impacts: 

  • Atmosphere: It sent ash and water vapour halfway to space, and generated tsunami waves across the globe.
  • On the seafloor: It is scoured and sculpted by violent debris flows out to a distance of over 80km.
  • Pyroclastic density currents: Hot lava when comes in contact with cold water of the ocean creates water vapour at very high temperatures. This creates a frictionless steam cushion on which lawa could flow at very high speed and to a very far distance.

Four ways water is displaced due to underwater volcano (thus causing tsunami):

  • By the density flows pushing the water out of the way
  • Through the explosive force of the eruption also pushes on the water
  • As a result of the dramatic collapse of the caldera floor (it dropped by 700m in the case of Tonga Volcano). By pressure waves from the atmospheric blast acting on the sea surface.

What is the Ring of Fire?

  • The Ring of Fire is a Pacific region home to over 450 volcanoes, including three of the world’s four most active volcanoes – Mount St. Helens in the USA, Mount Fuji in Japan and Mount Pinatubo in the Philippines. It is also sometimes called the circum-Pacific belt.
  • Around 90% of the world’s earthquakes occur in the Ring of Fire, and 80% of the world’s largest earthquakes.

Location:

  • It stretches along the Pacific Ocean coastlines, where the Pacific Plate grinds against other, smaller tectonic plates that form the Earth’s crust – such as the Philippine Sea plate and the Cocos and Nazca Plates that line the edge of the Pacific Ocean.
  • The 40,000 kilometre horse-shoe-shaped ring loops from New Zealand to Chile, passing through the coasts of Asia and the Americas on the way.

Risk:

  • The people most at risk from activity in the Ring of Fire are in the US west coast, Chile, Japan and island nations including the Solomon Islands. 
  • These areas are most at risk because they lie on so-called subduction zones – which are boundaries that mark the collision between two of the planet’s tectonic plates.

How was the Ring of Fire formed?

  • The Ring of Fire is the result from subduction of oceanic tectonic plates beneath lighter continental plates. The area where these tectonic plates meet is called a subduction zone.

Why does the Ring of Fire trigger earthquakes?

  • The world’s deepest earthquakes happen in subduction zone areas as tectonic plates scrape against each other – and the Ring of Fire has the world’s biggest concentration of subduction zones.
  • As energy is released from the earth’s molten core, it forces tectonic plates to move and they crash up against each other, causing friction. 
  • The friction causes a build-up of energy and when this energy is finally released it causes an earthquake. If this happens at sea it can cause devastating tsunamis.
  • Tectonic plates usually only move on average a few centimetres each year, but when an earthquake strikes, they speed up massively and can move at several metres per second.

Tonga Volcanic Eruption

Why in News?

  • Recently, a volcano erupted in the southern Pacific Island of Tonga, which triggered Tsunami waves around the Pacific.

About the News:

  • It is an Undersea Volcanic Eruption consisting of two small uninhabited islands, Hunga-Ha’apai and Hunga-Tonga.
  • The Tonga Islands occur along the Ring of Fire—a perimeter of heightened volcanic and seismic activity that encircles the Pacific Ocean basin.

What is the Ring of Fire?

  • The Ring of Fire is a Pacific region home to over 450 volcanoes, including three of the world’s four most active volcanoes – Mount St. Helens in the USA, Mount Fuji in Japan and Mount Pinatubo in the Philippines. It is also sometimes called the circum-Pacific belt.
  • Around 90% of the world’s Earthquakes occur in the Ring of Fire, and 80% of the world’s Largest Earthquakes.

Location:

  • It stretches along the Pacific Ocean coastlines, where the Pacific Plate grinds against other, smaller tectonic plates that form the Earth’s crust – such as the Philippine Sea plate and the Cocos and Nazca Plates that line the edge of the Pacific Ocean.

  • The 40,000 kilometre horse-shoe-shaped ring loops from New Zealand to Chile, passing through the coasts of Asia and the Americas on the way.

Risk:

  • The people most at risk from activity in the Ring of Fire are in the US west coast, Chile, Japan and island nations including the Solomon Islands.
  • These areas are most at risk because they lie on so-called subduction zones – which are boundaries that mark the collision between two of the planet’s tectonic plates.

How was the Ring of Fire formed?

  • The Ring of Fire is the result from subduction of Oceanic Tectonic Plates beneath lighter Continental Plates. The area where these Tectonic Plates meet is called a subduction zone.

Why does the Ring of Fire Trigger Earthquakes?

  • The world’s deepest earthquakes happen in subduction zone areas as tectonic plates scrape against each other – and the Ring of Fire has the world’s biggest concentration of subduction zones.
  • As energy is released from the earth’s molten core, it forces tectonic plates to move and they crash up against each other, causing friction. The friction causes a build-up of energy and when this energy is finally released it causes an earthquake. If this happens at sea it can cause devastating tsunamis.
  • Tectonic plates usually only move on average a few centimetres each year, but when an earthquake strikes, they speed up massively and can move at several metres per second.

INDIA TO RECEIVE NORMAL MONSOON, FORECASTS IMD

Why in News?

  • India will likely to have a normal monsoon, with a chance of ‘above normal’ rain in August and September, the India Meteorological Department (IMD) said recently.

About IMD:

  • IMD is an agency of the Ministry of Earth Sciences of the Government of India established in 1875.
  • It is the principal agency responsible for meteorological observations, weather forecasting and seismology.

Monsoon in India:

  • The climate of India is described as the ‘monsoon’ type. In Asia, this type of climate is found mainly in the south and the southeast.
  • Out of a total of 4 seasonal divisions of India, monsoon occupy 2 divisions, namely,
    • The Southwest Monsoon Season– Rainfall received from the southwest monsoons is seasonal in character, which occurs between June and September.
    • The Retreating Monsoon Season– The months of October and November are known for retreating monsoons.

Factors Influencing South-West Monsoon Formation:

  • The differential heating and cooling of land and water creates a low pressure on the landmass of India while the seas around experience comparatively high pressure.
  • The shift of the position of Inter Tropical Convergence Zone (ITCZ)in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator.
  • It is also known as the monsoon-trough during the monsoon season).
    • The Inter Tropical Convergence Zone (ITCZ,) is a broad trough of low pressure in equatorial latitudes. This is where the northeast and the southeast trade winds This convergence zone lies more or less parallel to the equator but moves north or south with the apparent movement of the sun.

IMD’s Forecast on Monsoon:

  • The IMD’s confidence stems largely from global weather models pointing to negligible chances of El Nino, a warming of the central equatorial Pacific that’s associated with the drying up of monsoon rain.
    • El Nino is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.
    • ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas.
    • The presence of the El Nino leads to an increase in sea-surface temperatures and weakening of the trade winds in the region.
    • IMD has also officially redefined the definition of what constitutes ‘normal’ rainfall and reduced it by 1 cm to 88 cm.
    • “Quantitatively, the monsoon seasonal rainfall is likely to be 100% of the Long Period Average (LPA) with a model error of ± 5%. The LPA of the season rainfall over the country as a whole for the period 1961-2010 is 88 cm.
  • It also gave new dates for the monsoon’s onset in several cities as part of an update, which it said was essential for a variety of economic activities ranging from agricultural planning to power distribution.

Change in Dates of Monsoon:

  • The onset over Kerala, which marks the arrival of the monsoon into mainland India, will continue to be June 1.
  • However, the onset date in Mumbai — historically June 10 — will now be June 11. The official withdrawal date is now delayed by over a week to October 8, instead of September 29.
  • The onset over Chennai has been delayed by three days — from June 1 to June 4. Ahmedabad will see the monsoon arrive nearly a week late — June 21 instead of June 14. Bhopal, too, is seeing a similar delay — to June 22 instead of June 15. Delhi, too, will see a four-day delay in the monsoon’s arrival to June 27.
  • “New monsoon advance dates over States like Maharashtra, Gujarat, Madhya Pradesh, Chhattisgarh, Telangana, Andhra Pradesh, Odisha, Jharkhand, Bihar and parts of Uttar Pradesh are delayed by three-seven days compared to existing normal dates”.
  • A significant delay in the withdrawal of the monsoon over northwest and central India has been observed. “Monsoon withdraws from NW India almost 7-14 days later from the existing dates. There is no change in the final withdrawal date over south India, i.e., 15th October”.

What Would be the Possible Impacts?

  • About 64% of people in India depend on agriculture for their livelihood and agriculture itself is based on Monsoon.
  • Agricultural prosperity of India depends very much on timely and adequately distributed rainfall. If it fails, agriculture is adversely affected particularly in those regions where means of irrigation are not developed.
  • The forecast on the monsoon by the IMD helps the agriculturists and farmers to do the farming activities according to the availability of Monsoon.
  • All the economic activities and Power distribution can be planned according the change of the Monsoon Dates.

NEW MONSOON DATES TO BE ANNOUNCED

Why in News?

  • The Earth Sciences Secretary has announced that the India Meteorological Department (IMD) has decided to revise the normal onset and withdrawal dates for the monsoon in some parts of the country from this year.

Highlights:

  • The four-month southwest monsoon season, which brings as much as 70 per cent of the country’s annual rainfall, officially begins on June 1, with the onset over Kerala, and ends on September 30.
  • The monsoon takes about a month and half after onset on the Kerala coast to cover the entire country and about a month, beginning from the north-western parts of the country on September 1, to withdraw completely.
  • Although the June 1 date for the onset of the monsoon on the Kerala coast is unlikely to be changed, the dates for onset in many other parts of the country are expected to be revised. Adjustments are likely to be made for many other parts of the country as well. Similar changes are expected in the withdrawal dates.
  • Effectively, the monsoon is now expected to have later arrival and withdrawal dates in most parts of the country.

Reason for Changes:

  • The Main Reason for the revision in the normal dates is the changes in precipitation patterns that have been taking place over the last many years.
  • In the last 13 years, for example, only once has the onset over the Kerala coast happened on June 1. While two or three days of earlier or later onset falls within the yearly variability, in several years the onset happened five to seven days late.
  • Similarly, the commencement of withdrawal has happened in the first week of September only twice during this period, and last year, the withdrawal started as late as October 9 and was completed in around just a week.
  • One of the significant changes being noticed is that rainfall is getting increasingly concentrated within a narrow band of days within the monsoon season. So, there are extremely wet days followed by prolonged periods of dry days.
  • Areas that have traditionally received plenty of rainfall are often remaining dry, while places that are not expected to get a lot of monsoon rain have sometimes been getting flooded.

Impact of the Changes:

  • New dates will likely nudge farmers in some parts of the country to make slight adjustments in the time of sowing their crops.
  • If the rainfall over the rice-growing regions occurs very late, then the transplantation of rice would be affected, which in turn could hit the crop yield.
  • Water management agencies managing the dams in the central plains, should now expect more rain only in the latter part of June.
  • Instead of planning only until the start of June, they would now be prompted to preserve and hold on to some water until later in the month.
  • The change in normal dates of the onset and withdrawal of the monsoon would help people understand when to expect rains, and to plan their activities accordingly.

MADDEN JULIAN OSCILLATION (MJO)

Why in News?

  • Warming in Indo-Pacific Ocean is altered the Madden Julian Oscillation.

About:

  • Northeast monsoon is the lifeline for Southern part of India, which is witnessing an increase in frequency of tropical cyclones.
  • Ind-Pacific Ocean is warming rapidly and there is a near two -fold expansion of warm pool.
  • The study, led by Roxy Mathew Koll of the Indian Institute of Tropical Meteorology, and published in the journal Nature, reports a two-fold expansion of the Indo-Pacific warm pool — the largest expanse of the warmest ocean temperatures on Earth.
  • The warm pool has expanded to become double its size, from 2.2 × 107 km2 during 1900-1980 to 4 × 107 km2 during 1981-2018, says the study.
  • This fold expansion is compared to an area equal to the size of Japan.
  • According to the study the entire Bay of Bengal becomes part of this giant warm pool, aiding rapid intensification of cyclones.
  • It covers most parts of Bay of Bengal, which is affecting climatic patterns.

MJO:

  • It is a Phenomenon, that have it can have dramatic impacts in the mid-latitudes.
  • Several times a year the MJO is a strong contributor to various extreme events in the United States, including Arctic air outbreaks during the winter months across the central and eastern portions of the United States.
  • It is characterized by a band of rain clouds moving eastward over the tropics.
  • It regulates tropical cyclone, the monsoons and the El Nino cycle and contributes to severe weather events over Asia, Australia, Africa, Europe and America.
  • Imagine ENSO as a person riding a stationary exercise bike in the middle of a stage all day long.
  • His unchanging location is associated with the persistent changes in tropical rainfall and winds is being linked to ENSO.
  • Now imagine another bike rider entering the stage on the left and pedaling slowly across the stage, passing the stationary bike (ENSO), and exiting the stage at the right.
  • This bike rider we will call the MJO and he may cross the stage from left to right several times during the show.
  • So, unlike ENSO, which is stationary, the MJO is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average.
  • This atmospheric disturbance is distinct from ENSO, which once established, is associated with persistent features that last several seasons or longer over the Pacific Ocean basin.
  • There can be multiple MJO events within a season, and so the MJO is best described as intraseasonal tropical climate variability that it varies on a week-to-week basis.
  • It is first discovered in the early 1970s by Dr. Roland Madden and Dr. Paul Julian when they were studying tropical wind and pressure patterns.
  • They often noticed regular oscillations in winds (as defined from departures from average) between Singapore and Canton Island in the west central equatorial Pacific (Madden and Julian, 1971; 1972; Zhang, 2005).
  • It consists of two parts, or phases: one is the enhanced rainfall or convective phase and the other is the suppressed rainfall phase.
  • Strong MJO activity often dissects the planet into halves: one half within the enhanced convective phase and the other half in the suppressed convective phase.
  • These two phases produce opposite changes in clouds and rainfall and this entire dipole that is having two main opposing centres of action propagates eastward.
  • The location of the convective phases is often grouped into geographically based stages that climate scientists

Warm Pool:

  • A mass of ocean water located in the western Pacific Ocean and eastern Indian Ocean which consistently exhibits the highest water temperature over the largest expanse of earth’s surface.
  • It is widely known as Tropical warm Pool or Indo-Pacific Warm Pool.

ATLANTIC MERIDIONAL OVERTURNING CIRCULATION (AMOC)

Why in News?

  • While greenhouse warming caused by human activity is heating up the Indian oceans, it is likely to boost a key system of currents in the Atlantic Ocean that plays a key role in determining the weather across the world.

Atlantic Meridional Overturning Circulation (AMOC):

  • AMOC is sometimes referred to as the “Atlantic conveyor belt”.
  • It is one of the Earth’s largest water circulation systems where ocean currents move warm, salty water from the tropics to regions further north, such as western Europe and sends colder water south.
  • It aids in distributing heat and energy around the earth, as the warm water it carries releases heat into the atmosphere, and in absorbing and storing atmospheric carbon
  • For thousands of years, AMOC has remained stable, but since the past 15 years, it has been weakening.
  • This change could have dramatic consequences for Europe and other parts of the Atlantic rim.

Impact of AMOC slowdown:

  • AMOC last witnessed a slowdown 15,000 to 17,000 years ago.
  • It caused harsh winters in Europe, with more storms or a drier Sahel in Africa due to the downward shift of the tropical rain belt.
  • The mere possibility that the AMOC could collapse should be a strong reason for concern in an era when human activity is forcing significant changes to the Earth’s systems.

Need for delaying AMOC slowdown:

  • Researchers found that rising temperatures in the Indian Ocean can help boost the AMOC and delay slow down.
  • Warming in the Indian Ocean generates additional precipitation, which, in turn, draws more air from other parts of the world, including the Atlantic.
  • This higher level of precipitation in the will reduce precipitation in the Atlantic and increase salinity in the waters.
  • This saline water in the Atlantic, as it comes north via AMOC, will get cold much quicker than usual and sink faster, acting as a jump start for AMOC, intensifying the circulation.

Uncertainty ahead:

  • Scientists don’t know for how long this enhanced warming in Indian Ocean will continue.
  • If other tropical oceans’ warming, especially the Pacific’s, catches up with the Indian Ocean, the advantage for AMOC will stop.
  • Moreover, it isn’t clear whether slowdown of AMOC is caused by global warming alone or it is a short-term anomaly related to natural ocean variability.

MAPPING LIGHTNING ACROSS INDIA

Why in News?

  • For the first time, a report has mapped lightning strikes across the country, and the lives they have claimed. It is a first-of-its-kind report on lightning incidents which has been prepared by Climate Resilient Observing Systems Promotion Council (CROPC), a non-profit organisation that works closely with India Meteorological Department (IMD).

Highlights of The Report:

  • According to the report lightning strikes have caused at least 1,311 deaths in the four-month period between April and July this year. UP accounted for 224 of these deaths, followed by Bihar (170), Odisha (129) and Jharkhand (118).
  • It counted 65.55 lakh lightning strikes in India during this four-month period, of which 23.53 lakh (36 per cent) happened to be cloud-to-ground lightning, the kind that reaches the Earth. The other 41.04 lakh (64 per cent) were in-cloud lightning, which remains confined to the clouds in which it was formed.
  • Odisha recorded over 9 lakh incidents of lightning (both kinds), the maximum for any state but fewer deaths than Uttar Pradesh, which had 3.2 lakh incidents.
  • Between 2,000 and 2,500 people are estimated as killed every year in lightning strikes in the country.
  • Observations confirm that the Chhotanagpur plateau, which is the confluence of Jharkhand, Odisha, part of Chhattisgarh and West Bengal and is inhabited by tribals, is the most lightning-prone area.
  • The area is electrostatically and thermodynamically charged, resulting in lightning. East Singhbhum has the highest number of lightning strikes — more than 2 lakhs — compared to any other district in India.
  • These areas are predominantly inhabited by tribals who need to be relocated to safer spaces, else their population will go extinct.

Significance of The Report:

  • The report is part of an effort to create a database that can help develop an early warning system for lightning, spread awareness, and prevent deaths.
  • It is possible to predict, 30-40 minutes in advance, when a lightning strike heads towards Earth.
  • The prediction is made possible through study and monitoring of the in-cloud lightning strikes.
  • Timely dissemination of this information can save several lives.
  • After carrying out a pilot project in 16 states, the IMD has begun providing lightning forecasts and warnings through mobile text messages from this year.
  • However, this is not yet available in all regions, and there isn’t enough awareness as yet on the kinds of action that need to be taken after an alert.

Connection Between Lightning and Climate Change:

  • It has been found that areas prone to heatwaves were also prone to lightning.
  • Pollution increases aerosols in the atmosphere, which in turn increases lightning.
  • There have been at least two or three instances of lightning strikes without rainfall, killing persons in Jharkhand.

How Is Lightning Formed?

  • Lightning is a very rapid and massive discharge of electricity in the atmosphere. Some of it is directed towards the Earth.
  • It is a result of the difference in electrical charge between the top and bottom of a cloud. The lightning-generating clouds are typically about 10-12 km in height, with their base about 1-2 km from the Earth’s surface. The temperatures at the top range from -35°C to -45°C.
  • As water vapour moves upwards in the cloud, it condenses into water due to decreasing temperatures. A huge amount of heat is generated in the process, pushing the water molecules further up. As they move to temperatures below zero, droplets change into small ice crystals.
  • As they continue upwards, they gather mass, until they become so heavy that they start descending. It leads to a system where smaller ice crystals move upwards while larger ones come down. The resulting collisions trigger release of electrons, in a process very similar to the generation of electric sparks. The moving free electrons cause more collisions and more electrons; a chain reaction is formed.
  • The 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 billions of volts. In little time, a huge current, of the order of lakhs to millions of amperes, starts to flow between the layers.
  • It produces heat, leading to the heating of the air column between the two layers of cloud. It is because of this heat that the air column looks red during lightning. The heated air column expands and produces shock waves that result in thunder sounds.

How Does Lightning Strike Earth?

  • The Earth is a good conductor of electricity. While electrically neutral, it is relatively positively charged compared to the middle layer of the cloud. As a result, an estimated 20-25 per cent of the current flow gets directed towards the Earth. It is this current flow that results in damage to life and property.
  • Lightning has a greater probability of striking raised objects on the ground, such as trees or buildings. Once they are sufficiently near the ground, about 80-100 m from the surface, they even tend to redirect their course to hit the taller objects. This is because travelling through air, which is a bad conductor of electricity, the electrons try to find a better conductor and also the shortest route to the relatively positively charged Earth’s surface. Thousands of thunderstorms occur over India every year. One thunderstorm can involve more than 100 lightning strikes.

EL NINO

  • Context: A weak El Nino prevailing in the Pacific Ocean since the start of this year is beginning to dissipate. Over the next two months, a fully neutral condition is likely to be restored in the Pacific Ocean, according to the latest bulletin issued by the Climate Prediction Centre of the National Oceanic and Atmospheric Administration of the US.

What is El Nino:

  • El Nino is a condition wherein the surface waters in the equatorial Pacific Ocean, off the coast of South America, become unusually warm.
  • Its opposite condition, when it becomes unusually cold, is termed, La Nina.
  • The two conditions influence weather events worldwide, including the Indian monsoon.
  • El Nino is known to suppress rainfall during the monsoon months.

Why A Weak El Nino Is Good for India?

  • The beginning of dissipation of El Nino is good news for India which is hoping to get good rainfall in the remaining part of the monsoon season after a deficient first month.
  • In June, rainfall in India had been 32 per cent below normal, though it was not on account of El Nino which has remained weak since it developed at the start of the year.
  • But a continuing El Nino, even if weak, could be a cause for concern for the remaining season as well.
  • As of now, the cumulative deficit in the rainfall this monsoon season for the country as a whole is 12 per cent.
  • The last couple of weeks, though, have brought good rainfall in many parts of the country. Overall, rainfall in the last week was 28 per cent above normal.

SUMMER SOLSTICE

  • Summer   Solstice   21   June   is   longest   Day   in   Northern hemisphere of globe.
  • In the northern hemisphere, summer solstice, or longest day of the year, takes place between June 20 and 22 each year.

What Exactly Happens:

  • Summer Solstice
  • There are two solstices each year – one in the winter and one in the summer. The summer solstice occurs when the tilt of Earth’s axis is most inclined towards the sun and is directly above the Tropic of Cancer.
  • It might seem like a day to celebrate, but it actually signals the moment the sun’s path stops moving northward in the sky, and the start of days becoming steadily shorter as the slow march towards winter begins.

Winter Solstice-

  • At the winter solstice, the Earth’s axis is tilted furthest away from the sun directly over the Tropic of Capricorn bringing only a few hours of daylight.
  • In the southern hemisphere the dates of the two solstices are reversed. The winter solstice occurs on the same day in June and the summer solstice the same day in December.
  • The term ‘solstice’ derives from the Latin word ‘solstitium’, meaning ‘sun standing still’. Some prefer the more teutonic term ‘sunturn’ to describe the event.

CYCLONE VAYU TO BE VERY SEVERE: IMD

Why in News:

  • IMD has officially informed that cyclone Vayu has changed course and now it will not make landfall in Gujarat

Back ground:

  • Vayu is a severe cyclonic storm heading towards Gujarat from the Arabian Sea.
  • The coastal districts of the State are likely to see heavy rainfall with high wind speed, and the sea will remain turbulent for the next 24 hours.
  • Cyclone Vayu will pass near Veraval, Porbandar and Dwarka. Its effect will be seen on the coastal regions, as there will be strong wind speed and heavy rain.
    IMD has officially informed that cyclone Vayu has changed course and now it will not make landfall in Gujarat.
  • The IMD said very severe category l cyclonic storm Vayu forming over east central Arabian Sea had moved north to northwest-wards in the past six hours.
  • It was 130 km south west of Veraval and 180 km south of Porbandar. It may move north- northwestwards for some time and skirt the Saurashtra coast later.
  • At Veraval, gusts with speed of 70 kmph were registered. Rain has started and will increase. South Gujarat may also get rain. Although the cyclone is not likely to make landfall, there will be heavy rain and strong winds.

Impact:

  • The Gujarat government said all its preparations will remain on stand-by mode till the cyclone passed completely. “However, while skirting through the Gujarat coast, it may cause strong winds and rain. All forces will remain on alert mode until the situation becomes normal. The storm was expected to make landfall between Veraval and Dwarka coast on Thursday afternoon, with wind speeds of 145-155 kmph and up to 175 kmph.

Precautionary Measures:

  • In precautionary measures, the State government shifted more than 2.5 lakh people from low-lying areas and vulnerable places to safer locations.
  • Deployed 36 National Disaster Response Force teams and other agencies.
    All trains in Saurashtra coast were cancelled, flight operations at all airports in the region suspended and port operations halted across the coast.
  • The government had also ordered schools and colleges to remain shut for two days.
  • The State authorities have swung into action, ordering closure of schools for three days in coastal districts and deploying teams of the National Disaster Response Force (NDRF) and asking fishermen to return to the coast from high seas.

CYCLONE VAYU

Why in News:

  • Cyclone Vayu (It is still to develop into a cyclone and is only a deep depression as of now) is currently positioned around 250 km northwest of Aminidivi island in Lakshadweep and about 750 km southwest of Mumbai.

Background: / Cyclone Vayu

  • Cyclone Vayu is slated to reach the Gujarat coast by either around midnight of June 12 or early morning of June 13.
  • It is likely to dissipate very fast after that because the land and atmosphere in the area was devoid of any moisture that can sustain it any further.
  • The northward progression of monsoon can be expected two to three days after that
  • Vayu is much weaker than Fani. At its strongest, it is likely to generate winds of speed 110- 120 km per hour, according to current forecasts. In contrast, winds associated with Fani had speeds of about 220 km per hour.
  • Vayu, even at its most powerful, therefore would only be categorised as a “severe cyclonic storm”, while Fani was an “extremely severe cyclonic storm” and almost satisfied the conditions for classification as a “super cyclone”.
  • The lowest official classification used in the North Indian Ocean is a Depression, which has 3-minute sustained wind speeds of between 31–49 km/h
    Deep Depression, which has winds between 50–61 km/h Cyclonic storm, wind speeds of between 62–88 km/h
  • Severe Cyclonic Storms have storm force wind speeds of between 89–117 km/h Very Severe Cyclonic Storms have hurricane-force winds of 118–166 km/h Extremely Severe Cyclonic Storms have hurricane-force winds of 166–221 km/h
  • The highest classification used in the North Indian Ocean is a Super Cyclonic Storm, which have hurricane-force winds of above 222 km/h

Impact of Cyclone Vayu on Monsoon:

  • While Vayu is unlikely to result in widespread destruction, the cyclone is expected to interfere with normal progression, by sucking all the moisture from the monsoon winds towards itself.
  • Cyclones are sustained by very strong low-pressure areas at their core. Winds in surrounding areas are forced to rush towards these low-pressure areas.
  • Similar low-pressure areas, when they develop near or over land, are instrumental in pulling the monsoon winds over the country as well.
  • But right now, the low-pressure area at the centre of the cyclone is far more powerful than any local system that can pull the monsoon winds moving northeast.

Arabian Sea Cyclones:

  • Though cyclones are common in the June, very few of them originate in the Arabian Sea as compared to Bay of Bengal.
  • In the last 120 years for which records are available, just about 14% of all cyclonic storms, and 23% of severe cyclones, around India have occurred in the Arabian Sea.
  • Arabian Sea cyclones are relatively weak compared to those emerging in the Bay of Bengal. Also, most of the cyclones emerging in the Arabian Sea are headed towards Gujarat Coastline. As Gujarat Coastline is not very densely populated, the damage potential of the cyclones on the western coast is comparatively low.

HEAT WAVE TO CONTINUE FOR A COUPLE OF DAYS: IMD

Why in News:

  •    The India Meteorological Department (IMD) said severe heat wave conditions will continue in many parts, especially in Rajasthan and several parts of north and central India, In worst-hit Rajasthan, while Churu recorded the highest temperature of 48.4°C.

Details:

  •    In worst-hit Rajasthan, a farmer died of heatstroke in Sikar district, while Churu recorded the highest temperature of 48.4°C.

India Meteorological Department (IMD)

  •    The IMD is the national meteorological service of the country and it is the chief government agency dealing in everything related to meteorology, seismology and associated subjects.
  •    It was formed in 1875.
  •    The IMD is under the Ministry of Earth Sciences, Government of India

IMD Mandate:

  •    Taking meteorological observations and providing current information and forecasting information for the most favorable operation of weather-dependent activities such as irrigation, agriculture, aviation, shipping, offshore oil exploration and so on.
  •    Offering warning against severe weather phenomenon such as tropical cyclones, dust storms, norwesters, heat waves, cold waves, heavy rains, heavy snow, etc.
  •    Providing met-related statistics needed for agriculture, industries, water resources management, oil exploration, and any other strategically important activities for the country. Engaging in research in meteorology and allied subjects.

Heat Wave:

  •    Heat wave is considered if maximum temperature of a station reaches at least 40°C or more for Plains, 37°C or more for coastal stations and at least 30°C or more for Hilly regions. Following criteria are used to declare heat wave:

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.

Based on Actual Maximum Temperature (for plains only):

  1. Heat Wave: When actual maximum temperature ≥ 45°C
  2. Severe Heat Wave: When actual maximum temperature ≥47°C
  •    To declare heat wave, the above criteria should be met at least in 2 stations in a Meteorological sub-division for at least two consecutive days and it will be declared on the second day.
  •    A Heat Wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India. Heat Waves typically occur between March and June, and in some rare cases even extend till July. The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.
  •    Detection and location of earthquakes and evaluation of seismicity in various parts of the country for developmental projects.

How do heat waves affect us?

  •    The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke. The signs and symptoms are as follows:
  •    Heat Cramps: Ederna (swelling) and Syncope (Fainting) generally accompanied by fever below 39*C i.e.102*F.
  •    Heat Exhaustion: Fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
  •    Heat Stoke: Body temperatures of 40*C i.e. 104*F or more along with delirium, seizures or coma. This is a potential fatal condition.
  •    Heat waves killed 1,422 in Andhra Pradesh and 541 in Telangana in 2015 or about 90% of all the heat wave mortality of that year.

MONSOON TO REACH KERALA

Why in News:

Monsoon rains in India are likely to be “normal” this year says India Meteorological Department (IMD)

Background:

How does IMD calculate monsoon level?

  • The India Meteorological Department (IMD) expresses the projected rainfall in terms of Long Period Average (LPA). The LPA is the average rainfall recorded during the months from June to September, calculated during the 50- year period from 1951 to 2000.
  • LPA is kept as a benchmark while forecasting the quantitative rainfall for the monsoon season every year. The LPA of the monsoon season over the entire country is 89 cm.
  • Like the countrywide figure, IMD maintains an independent LPA for every homogeneous region of the country.
  • E.g. 143.83 cm, 97.55 cm, 71.61 cm, and 61.5 cm for East and Northeast India, Central India, South Peninsular India, and Northwest India respectively.
  • Going by this, IMD maintains five rainfall distribution categories on an all-India scale. These are:
  • Normal or Near Normal – when there is +/-10% departure of actual rainfall i.e. between 96-104% of LPA
  • Below normal – when departure of actual rainfall is less than 10% of LPA i.e. 90-96% of LPA
  • Above normal – when actual rainfall is 104-110% of LPA
  • Deficient – when departure of actual rainfall is less than 90% of LPA Excess – when departure of actual rainfall is more than 110% of LPA

Rationale:

  • The IMD’s optimism is based on global climate models projecting a ‘weakening El Nino.’
  • The El Nino, a cyclic warming of the Central and Eastern Pacific region, has historically been linked to a weakening of monsoon rain.
  • A temperature rise greater than 1°C for 3 months is considered a ‘strong’ El Nino and a threat to the monsoon. A 0.5°C-1°C rise is called weak El Nino conditions; currently the El Nino is 0.9 C. The IMD’s models in March, expect the El Nino to peak around May and then recede for the rest of the monsoon months.
  • Globally too, other models expect El Nino to recede after June or July.
  • All these suggest the possibilities of a normal as opposed to below normal monsoon rains in India this year. Another factor, called a positive Indian Ocean Dipole (IOD) (warming in the western Arabian ocean) could neutralise the potential negative impact from the El Nino.

SAUDI ARABIA SAYS TWO OIL TANKERS ATTACKED NEAR UAE

Why in News:

  • Saudi Arabia said two of its oil tankers (near hormuz strait) came under attack off the coast of the United Arab Emirates, describing the assault as a “dangerous threat” to the security of international crude supplies as regional tensions spike in the Gulf.

Background: / Hormuz strait:

  • Contiguous Landmass: Iran and the UAE.
  • Joining Seas/Water Bodies: The Gulf of Oman and the Persian Gulf

Importance of strait of Hormuz:

  • The Strait of Hormuz is a strategically important strait or narrow strip of water that
    links the Persian Gulf with the Arabian Sea and the Gulf of Oman.
  • The strait is only 21 to 60 miles (33 to 95 km) wide throughout its length. The Strait of Hormuz is important because it is a geographic choke point and a main artery for the transport of oil from the Middle East.
  • Iran and Oman are the countries nearest to the Strait of Hormuz and share territorial rights over the waters.
  • Due to its importance, Iran has threatened to close the Strait of Hormuz several times in recent history.

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