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

Central Idea

• Cyclone Michaung (name suggested by Myanmar) makes landfall in Tamil Nadu and Andhra Pradesh.
• Michaung is the fourth tropical cyclone over the Bay of Bengal this year.

About Cyclone Michaung

• Uncommon Intensity: December cyclones in the North Indian Ocean typically do not reach high intensities. Michaung, with its severe storm classification, is an exception.
• Upgraded Intensity: Initially predicted as a tropical cyclone, IMD upgraded Michaung to a ‘severe’ storm due to its unexpected intensification.
• Heat Index Contribution: The intensification is attributed to the above-normal heat index values off the southern Andhra Pradesh coast.

Indian Tropical Storms: An Overview

• Annual Cyclones: The North Indian Ocean basin averages about five cyclones per year, predominantly in the Bay of Bengal.
• Arabian Sea Cyclones: Though less frequent, Arabian Sea cyclones often reach higher intensities and can cause extensive damage.
• Peak Cyclone Seasons: Cyclones are most common during pre-monsoon (April-June) and post-monsoon (October-December) months, with May and November seeing more intense storms.

Factors Influencing Storm Intensification

• Ocean Heat: Cyclones draw energy from warm ocean temperatures, typically around 26 degrees Celsius or higher.
• Tropical Cyclone Heat Potential (TCHP): This oceanographic parameter is crucial in cyclone genesis and intensification.
• Complex Atmospheric Conditions: Various atmospheric factors like wind shear, convection, and air-sea interactions also play a role in cyclone development.
• Coriolis Effect: This effect influences cyclone formation in the northern hemisphere, causing air to move anticlockwise in low-pressure areas.

Back2Basics: Extratropical and Tropical Cyclones

• General Definition: Cyclones are large-scale air systems rotating around a low-pressure center, often accompanied by violent storms.
• Extratropical Cyclones: Found outside the tropics, these cyclones have a cold core and gain energy from interactions between cold and warm air masses. They can form over both land and sea.
• Tropical Cyclones: These form in tropical regions and are powered by the condensation of water vapor. They lack associated warm or cold fronts and are known as hurricanes or typhoons in different regions.

Cyclone Naming Process

• Rotational Basis for Naming: The naming of cyclones is done by countries on a rotational basis, following certain existing guidelines.
• Responsibilities of RSMCs and TCWCs: Worldwide, there are six regional specialized meteorological centers (RSMCs) and five regional Tropical Cyclone Warning Centers (TCWCs) mandated for issuing advisories and naming of tropical cyclones.
• IMD’s Role: IMD is one of the six RSMCs providing tropical cyclone and storm surge advisories to 13 member countries under the WMO/Economic and Social Commission for Asia-Pacific (ESCAP) Panel.
• Naming Authority of IMD: RSMC, New Delhi, is also mandated to name the tropical cyclones developing over the north Indian Ocean, including the Bay of Bengal and the Arabian Sea.
• Guidelines for Naming: Some rules are to be followed while naming cyclones, such as being neutral to politics, religious beliefs, cultures, and gender, avoiding offensive or cruel names, and keeping the name short and easy to pronounce.
• Future Naming: After ‘Michaung’, the next cyclone as per India’s suggestion will be named ‘Tej’.

Central Idea

• The Indian National Centre for Ocean Information Services (INCOIS), a division under the Ministry of Earth Sciences (MoES), has made a significant discovery regarding the Southern Annular Mode (SAM), a crucial climate pattern.
• Their research has revealed that SAM plays a pivotal role in influencing sea conditions across the Indian Ocean.

What is Southern Annular Mode (SAM)?

Role of Ocean Surface Waves

• Coastal Processes: Ocean surface waves are key players in shaping coastal processes, impacting shoreline erosion, sediment transport, coastal engineering, and recreational activities.
• Scientific Approach: The scientific team leveraged 40 years of data (1979 to 2018) from the European Centre for Medium-Range Weather Forecast.

Positive and Negative SAM Phases

• Positive SAM Phase: During a positive SAM phase, a cyclic pattern of warm sea surface temperature anomalies emerges, accompanied by strong winds that increase wave activity in the Indian Ocean. A new swell generation region along the east African coast contributes to heightened wave heights in the Arabian Sea.
• Negative SAM Phase: Conversely, during a negative SAM phase, the eastern tropical southern Indian Ocean becomes the primary region for generating swells, resulting in reduced wave heights in the Arabian Sea.

Significance of SAM

• Coastal Planning: Understanding SAM allows for better coastal planning, helping coastal communities prepare for the impact of changing sea conditions.
• Resource Management: SAM insights can aid in more efficient resource management, optimizing the utilization of marine resources.
• Disaster Preparedness: Knowledge of SAM patterns can enhance disaster preparedness efforts, enabling timely response to potential ocean-related disasters.
• Wave Predictions: The research contributes to improving wave predictions, offering advanced forecasting capabilities.
• Benefiting Stakeholders: Stakeholders in the blue economy, including shipping, maritime boards, and the oil industry, can optimize their multi-million-dollar operations at sea based on SAM insights.

Implications for Various Sectors

• Monsoon Season Impact: Typically, inland vessel operations and oil exploration activities face restrictions during the monsoon season.
• Fair Sea State Windows: Predicting SAM phases through the Ocean Forecasting System can identify “Fair Sea state windows” during monsoons.
• Impact on Blue Economy: These fair windows can be leveraged by oil and shipping industries, making a significant contribution to blue economy activities along the Indian coast

Central Idea

• Ball lightning, an intriguing natural phenomenon characterized by luminous spherical objects appearing during thunderstorms, has intrigued observers for generations.
• They are sometimes accompanied by hissing sounds and unusual odors, adding to the mystery surrounding their origin and behavior.

Understanding Lightning and Ball Lightning

• Normal lightning: Lightning is a natural electrical discharge that occurs due to differences in electrical charges within clouds or between clouds and the Earth’s surface during storms.
• Ball Lightning: Ball lightning has been documented in historical records, with instances dating back to 1638 when a “great ball of fire” entered an English church through a window, hinting at its potential danger.
• Scientific Recognition: While debates persist, most scientists acknowledge the existence of ball lightning, even though its underlying mechanisms are not fully understood.
• Chinese Research: A study conducted by researchers from Lanzhou’s Northwest Normal University in 2012 inadvertently captured a ball lightning event during a thunderstorm. Their findings confirmed the presence of elements such as silicon, iron, and calcium in the luminous sphere, matching the composition of local soil.

Possible Causes of Ball Lightning

• Ground Strike Theory: Some scientists propose that ball lightning may result from ground strikes, initiating chemical reactions between oxygen and vaporized soil elements. This process creates ionized air or plasma, resembling phenomena like St. Elmo’s Fire.
• Glass-Related Hypothesis: Another theory suggests that ball lightning might form due to the buildup of atmospheric ions on glass surfaces, creating an electrical field capable of generating discharges.
• Microwave Radiation: An alternative theory posits that ball lightning could be linked to microwave radiation produced when lightning strikes the Earth’s surface, potentially encapsulating it in a plasma bubble.

Association with Earthquakes

• In rare instances, ball lightning has been observed in connection with earthquakes, displaying as bluish flames, sudden bright flashes from the ground, or floating orbs.
• A 2014 study exploring earthquake lights proposed that specific rock types release electrical charges during seismic waves, leading to luminous displays.

Central Idea

• On October 15, Afghanistan was struck by a formidable earthquake with a magnitude of 6.3, adding to the woes of a nation still reeling from a series of devastating quakes just days earlier.
• This recent seismic activity reflects Afghanistan’s turbulent history of earthquakes, often with catastrophic consequences.

Understanding Earthquakes

• Tectonic Plate Movement: The Earth’s lithosphere consists of tectonic plates that move due to internal heat energy. Fault lines are formed along the discontinuities where these plates interact.
• Earthquake Mechanism: Earthquakes occur when these lithospheric plates suddenly slip past one another, releasing energy that propagates as seismic waves. The point where the slip starts is known as the focus or hypocenter, with the epicenter being its surface projection.

What exactly causes Earthquakes?

• As we know, the earth’s outermost surface, crust, is fragmented into tectonic plates.
• The edges of the plates are called plate boundaries, which are made up of faults.
• The tectonic plates constantly move at a slow pace, sliding past one another and bumping into each other.
• As the edges of the plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
• Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
• The location below the earth’s surface where the earthquake starts are called the hypocenter, and the location directly above it on the surface of the earth is called the epicentre.

Afghanistan’s Seismic Vulnerability

• Tectonic Plate Intersection: Afghanistan’s location atop the convergence of the Indian and Eurasian tectonic plates results in frequent seismic activity.
• Eurasian Plate: Afghanistan sits on the Eurasian Plate, with the Arabian Plate subducting northward in the west and the Indian Plate doing the same in the east.
• Complex Geology: The Hindu Kush mountain range and the Pamir Knot add complexity to this geological region, leading to folding, faulting, and earthquakes.
• Continual Compression: The northward movement of the Indian Plate toward Eurasia causes compression, uplifting the Himalayas, and transmitting tectonic stress. This leads to crustal deformation, faulting, and seismic activity.
• Active Fault Systems: Afghanistan is intersected by active fault systems like the Chaman Fault and the Main Pamir Thrust, which are prolific sources of earthquakes.

History of Earthquake Afghanistan

• October 11 Quakes: In October 2023, a series of powerful earthquakes, including a magnitude 6.3 tremor, wreaked havoc in Herat province, claiming the lives of at least a thousand people.
• June 2022 Tragedy: A magnitude 6.1 earthquake in Khost and Paktika provinces in June 2022 left over 1,000 casualties.
• 2015 Catastrophe: A major earthquake in northeastern Afghanistan in 2015 claimed over 200 lives in Afghanistan and northern Pakistan.
• 2002 Devastation: A 6.1-magnitude earthquake in 2002 resulted in approximately 1,000 casualties in northern Afghanistan.
• 1998 Disaster: In 1998, northeast Afghanistan experienced a catastrophic earthquake and subsequent tremors, causing the loss of at least 4,500 lives.

Central Idea

• India Meteorological Department (IMD) has announced withdrawal of the monsoon.

What is Monsoon Withdrawal/Retreat?

• In India, retreating monsoon is the withdrawal of south-west monsoon winds from North India.
• The withdrawal is gradual and takes about three months.
• With the retreat of the monsoons, the clouds disappear and the sky becomes clear. The day temperature starts falling steeply.
• Monsoon rains weaken all over India except few southeastern states.
• It is helpful in Rabi crop cultivation.

Factors affecting the retreat

Two predominant factors cause the phenomenon:

(1) Land topography

• First, the low mountain range in each region runs from north to south, shielding it from west-bound winds that trigger summer monsoon.
• After summer, the range aids in the ‘orographic lift’ or rising of east-bound air mass from a lower to higher elevation, forming clouds and resulting in rain.

(2) Atmospheric convection

• The second factor is atmospheric convection or vertical movement of air.
• As the earth is heated by the sun, different surfaces absorb different amounts of energy and convection may occur where the surface heats up very rapidly.
• As the surface warms, it heats the overlying air, which gradually becomes less dense than the surrounding air and begins to rise.
• This condition is more favorable from September to February because of the role played by sea surface temperature or water temperature.

Immediate factors influencing withdrawal

• The withdrawal of the monsoon is based on meteorological conditions such as-

1. Anti-cyclonic circulation (dry air that is the opposite of a cyclone)
2. Absence of rain in the past five days and
3. Dry weather conditions over the region

When does it occur?

• The monsoon withdrawal is a long-drawn process and extends into mid-October, though the IMD considers September 30 to be the final day of the season over India.
• The rain after that is categorised as “post-monsoon” rainfall.

Central Idea

• A devastating earthquake struck Morocco, resulting in significant casualties and damage.

Details of the Moroccan Earthquake

• Shallow Epicenter: The quake’s epicentre was near the town of Ighil, approximately 70 km southwest of Marrakech. It was considered fairly shallow, with varying depth estimates.
• Higher Energy: Shallow earthquakes are typically more dangerous as they carry more energy, making them more destructive compared to deeper quakes.

Major Causes

• Tectonic Convergence: The earthquake resulted from the northward convergence of the African plate with the Eurasian plate along a complex plate boundary.
• Faulting: The USGS attributed the quake to oblique-reverse faulting at a shallow depth within the Moroccan High Atlas Mountain range.
• Fault Classification: Oblique-slip faults exhibit characteristics of both dip-slip and strike-slip faults, occurring in areas of compression where tectonic plates converge.

Why discuss this?

• Low Seismicity: Earthquakes are uncommon in North Africa, with low seismicity rates along the northern margin of the continent.
• Historic Strength: This earthquake was the strongest ever recorded in the mountainous region, catching Morocco unprepared for such an event.
• Construction Vulnerabilities: Many Moroccan buildings, especially in rural areas and older cities, are not constructed to withstand strong tremors.

What is an Earthquake?

• An earthquake is an intense shaking of the ground caused by movement under the earth’s surface.
• It happens when two blocks of the earth suddenly slip past one another.
• This releases stored-up ‘elastic strain’ energy in the form of seismic waves, which spreads through the earth and cause the shaking of the ground.

What exactly causes Earthquakes?

• As we know, the earth’s outermost surface, crust, is fragmented into tectonic plates.
• The edges of the plates are called plate boundaries, which are made up of faults.
• The tectonic plates constantly move at a slow pace, sliding past one another and bumping into each other.
• As the edges of the plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
• Earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.
• The location below the earth’s surface where the earthquake starts are called the hypocenter, and the location directly above it on the surface of the earth is called the epicentre.

Central Idea

• In the ever-changing tapestry of Earth’s climate, the Fujiwhara effect has emerged as a captivating and consequential phenomenon.
• With cyclones intensifying due to global warming, this intricate ‘dance’ between cyclones is garnering attention.

Why in news?

• Surprising Weather: Recently, a storm named Hurricane Hilary brought a tropical twist to the US west coast. It’s part of a series of odd weather happenings there.
• Wet Weather: Earlier this year, California had an unexpected rainy season with lots of wet storms, called ‘atmospheric rivers.’
• Fujiwhara Show: During one of these storms, something special occurred—an effect named after a scientist. Let’s dive into the details.

Decoding the Fujiwhara Effect

• Cyclone Waltz: Imagine two cyclones (or big storms) spinning in the same direction. When they get close, they begin a kind of dance around a common center.
• Outcome of the Dance: Depending on the strength of the cyclones, they might merge, spin together, or one might absorb the other.
• Super Cyclone: Rarely, if both cyclones are super strong, they can become one mega cyclone that causes big trouble.

Historical Context and Impact

• Origins and Discovery: The Fujiwhara effect got its name from a Japanese scientist who first talked about it in 1921. It was seen happening for real in 1964.
• Effects Unleashed: This unusual dance can be fierce. It has caused strong winds, broken windows, and power problems in some areas.
• Guessing Game: The Fujiwhara effect is tricky for weather experts. It’s hard to predict what will happen when two cyclones dance together.

Climate Change Connection

• More Frequent Moves: The Fujiwhara effect is showing up more often now. Experts believe it’s because our world is getting hotter and ocean waters are warming up.
• Hotter Waters: Because of global warming, storms are getting stronger. For instance, in Taiwan, typhoons have become 35% stronger since 1977 due to warmer oceans.

Implications

• Nature’s Symphony: The Fujiwhara effect is like a nature’s concert, showing us how everything is connected in our climate.
• Future Twist: As storms get more powerful, the Fujiwhara effect could become even more important and harder to understand.
• Planet’s Dance: The Fujiwhara effect teaches us about our planet’s rhythm and how important it is to take care of our home.