Physical Geography

Aphelion

Context: Earth reaches aphelion every July. This year it did so on the 5th of July.

About Aphelion

Aphelion is the point in the orbit of a celestial body (like a planet or comet) that is farthest from the Sun. Earth reaches aphelion around early July each year.
Earth's aphelion happens because its orbit is elliptical, not circular. All planets in the solar system move in oval-shaped orbits around the Sun, and this is probably true for planets around other stars too.
Gravity is the reason behind these elliptical orbits. The planets pull on each other, making their orbits less circular. Jupiter, being the largest planet, has the most influence.
The shape of an orbit is measured by its eccentricity: the higher the eccentricity, the more oval-shaped the orbit is. Mars has an eccentricity of 0.094, meaning its orbit is more elliptical. Pluto's orbit is even more oval-shaped with an eccentricity of 0.244. In comparison, Earth's orbit is almost circular with an eccentricity of 0.017.

How far is the Earth from the Sun at aphelion?

At aphelion, Earth’s distance from the Sun is about 152.1 million km.
Six months later, in early January, Earth reaches perihelion, the point at which it is closest to the Sun. At perihelion, the distance between Earth and the Sun is roughly 147.1 million km.

Does aphelion affect temperatures on Earth?

The distance from the Sun is a common misconception for the cause of seasons.
At aphelion, Earth receives 7% less sunlight, leading to milder summers and winters in the Northern Hemisphere.
Earth is farthest from the Sun during aphelion, it doesn't cause the coldest weather. The distance change is actually too small to significantly impact global temperatures.
The main reason for seasons is the tilt of Earth's axis, not the slight variations in distance to the Sun. As Earth orbits the Sun, the tilt means different hemispheres receive more direct sunlight at different times. This creates the cycle of summer, fall, winter, and spring.

What would happen if there were no aphelion?

If Earth's orbit were a perfect circle, the lengths of seasons would be equal, right now, spring and summer are a few days longer than fall and winter in the Northern Hemisphere.
If Earth's orbit became more eccentric, seasons in the Southern Hemisphere would become extreme. This could lead to intolerable summers and winters, causing crop failures and freezes.

Context - Remal’s impact was severe in the Northeast because of its unusual trajectory. It developed over the east central Bay of Bengal on Saturday (May 25) evening and intensified into a severe cyclonic storm on Sunday morning over the north Bay of Bengal, with wind speeds clocking over 100 kmph

Unusual path of Remal

The bay was unusually warm with some parts recording a temperature of 32 degrees Celsius (warm for water) which contributed to the intensity of the cyclone. A severe cyclone will rapidly weaken after it interacts with land, but Remal maintained its intensity as it moved to the northeast, causing unprecedented heavy rainfall, landslides, mudslides and flooding in that region.

Note – Exact reason for Remal’s unusual trajectory is still under investigation. However a related concept of recurving of cyclone is important from the examination’s perspective.

About Recurving of Cyclones

One of the most important aspects of cyclone track forecasting is recurvature, A cyclone track is said to recurve when it changes its path from the predominant zonal flow (normally westwards) to predominant meridional flow (normally northwards) and often again back to zonal flow in the opposite direction (normally eastwards).

The recurvature is said to be abrupt if the meridional flow is short-lived and there is sudden change in the direction of more than 60°.

Tropical cyclones in both the Northern and Southern Hemispheres tend to move westward and drift slowly poleward and then eastward. Trade winds are responsible for the general westward motion of tropical cyclones (Environmental steering).

Reasons for Recurving.

Coriolis force drifts the cyclones towards right in N.H (Ferrell’s law) and hence pole wards and then eastwards (Beta Drift).
Presence of subtropical highs, over oceans poleward of the trade winds. These regions of clockwise circulation in the Northern Hemisphere make the winds on the western edges of these large-scale circulations move toward the poles.
Interaction of tropical cyclones with mid latitude westerlies change the original westward path of tropical cyclones towards north and then eastwards.
Upper air jet streams further push the cyclones towards right.
Interaction among several cyclonic wind system, a new avg point of centre is made and cyclones changes its path (Fujiwara effect).

Urban Heat Island

Context: Carbon Brief analysis revealed nearly 40% of the Earth hit its highest-ever daily temperature between 2013 to 2023.

About Urban Heat Island (UHI)

Definition:

An urban heat island refers to a phenomenon where urban areas experience significantly higher temperatures compared to surrounding rural areas.

Global Cases of rising temperature:

The United Kingdom crossed 40 degrees Celsius for the first time ever in July 2022.
A small town in China’s northwest recorded 52-degree Celsius last year, the highest ever for that country.
In 2021, Sicily in Italy recorded 48.8 degree Celsius, the highest for Europe ever.
Recent temperatures in New Delhi, notably a reported 52.9°C, raise concerns, pending verification. Doubts arise due to inconsistencies with other stations, with Safdarjung recording 46.8°C, an 80-year high.

Why does this happen?

The sun’s heat and light reach the city and the adjoining rural areas in the same way.
The difference in temperature between urban and less-developed rural areas has to do with how well the surfaces in each environment absorb and hold heat.
If you travel to a rural area, you’ll probably find that most of the region is covered with plants grasses, trees, and farmland.
Plants take up water from the ground through their roots and store the water in their stems and leaves. The water eventually travels to small holes on the underside of leaves.
There, the liquid water turns into water vapor and is released into the air. This process is called transpiration. It acts as nature’s air conditioner.

Development Process:

Daytime: During the day, urban surfaces absorb solar radiation, heating up and raising local temperatures. Buildings and structures trap heat, creating thermal energy reservoirs.
Nighttime: Urban areas release stored heat slowly, resulting in elevated nighttime temperatures compared to surrounding rural areas. This phenomenon is known as the "urban heat island effect.

Causes of UHI Development:

Human Activities: Urbanization leads to the creation of structures such as buildings, roads, and pavements, which absorb and retain heat.
Urban Canyon effect: The tall buildings within many urban areas provide multiple surfaces for the reflection and absorption of sunlight, increasing the efficiency with which urban areas are heated.
Modification of Land Surface: Urban development alters the land surface through the removal of vegetation, which reduces evaporative cooling and increases heat absorption.
Anthropogenic Heat: Activities like transportation, industrial processes, and energy consumption release heat, contributing to elevated temperatures.

Albedo Effect: Urban surfaces, such as concrete and asphalt, have lower albedo (reflectivity), absorbing more solar radiation and increasing temperatures.
Limited Green Spaces: The reduction of green spaces like parks and gardens decreases the cooling effect of vegetation and exacerbates heat retention.

Factors Influencing UHI Intensity:

Urban Morphology: The layout, density, and height of buildings influence UHI intensity. Compact urban areas with tall buildings tend to trap more heat.
Climate: Local climatic conditions, such as wind patterns and humidity, can affect the intensity of UHI.
Urban Design: Factors like street orientation, building materials, and green infrastructure can either exacerbate or mitigate UHI effects.

Impact of UHI:

Health Risks: Higher temperatures in urban areas can lead to heat-related illnesses and exacerbate air pollution, affecting public health.
- Urban Heat Islands (UHIs) exacerbate heat waves, increasing heat-related illnesses and fatalities.
- Heat exposure correlated with mental health issues and decreased academic performance.
- UHIs worsen air quality, accelerating pollutants' production and impacting health.
Energy Consumption: Increased cooling demands in urban areas result in higher energy consumption and associated greenhouse gas emissions.
Ecological Effects: UHI can disrupt ecosystems, alter local climate patterns, and affect biodiversity.
- Urban Heat Islands (UHIs) raise water temperatures, harming aquatic ecosystems.
- Rapid temperature changes due to UHIs stress aquatic life, causing fish kills.
- UHIs alter breeding strategies and habitat ranges of species.
Social Impacts: Vulnerable populations, such as the elderly and low-income communities, are disproportionately affected by UHI, exacerbating social inequalities.
- According to a study by the International Labour Organization (ILO), in 1995, the working hours lost in India due to heat stress were 5.87 per cent in agriculture and construction, 2.95 per cent in industry, and 0.63 per cent in services.
- These numbers are anticipated to increase to 9.04 per cent in agriculture and construction, 5.29 per cent in industry, and 1.48 per cent in services by 2030.

Mitigation Strategies:

Green Infrastructure: Increasing vegetation cover through parks, green roofs, and tree planting helps mitigate UHI effects by providing shade and enhancing evaporative cooling.
Urban Planning: Designing urban spaces to prioritize pedestrian-friendly environments, incorporating green spaces, and promoting sustainable building practices can reduce UHI intensity.
Cool Roofing and Materials: Using reflective roofing materials and heat-absorbing coatings on pavements can lower surface temperatures and mitigate heat absorption.
Heat Island Reduction Programs: Implementing policies and initiatives focused on reducing urban heat island effects, such as urban forestry programs and building codes promoting energy-efficient designs.

How Venezuela lost its last glacier, why this matters

Context: Venezuela has likely become the first country in modern history to lose all its glaciers. Scientists expected the Humboldt glacier to last another decade. However, it melted at a faster rate than expected.

About the News

Venezuela used to be home to six glaciers, located at about 5,000 metres above sea level in the Andes mountains. By 2011, five of them had vanished.

Last of these six glaciers is Humboldt glacier. The glacier had shrunk from 450 hectares to just 2 hectares. Now it has become too small to be classed as a glacier.

There is no universal consensus on how large a mass of ice has to be to qualify as a glacier, the United States Geological Survey (USGS) says a commonly accepted guideline is around 10 hectares.

Scientists expected the Humboldt glacier to last another decade. But it melted at a faster rate than expected, leading to its downgrade from a glacier to an ice field.

The concerning issue is that the other glaciers across the world are shrinking and disappearing faster than researchers thought.

According to one study published in the science journal in 2023 two-thirds of global glaciers are projected to melt out of existence by 2100 at current climate change trends.

Reason behind such shrink

Primary reason is global warming - The Andes Mountain range runs through parts of Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, and Venezuela. It has witnessed a temperature increase of a high rate of 0.10 degrees Celsius in the past seven decades. That is one of the major reasons why Venezuela has lost all of its glaciers.
In the case of the Humboldt glacier, the melting was accelerated by El Niño, which developed in July 2023.

Glaciers

A glacier is a large, perennial accumulation of crystalline ice, snow, rock, sediment, and often liquid water that originates on land and moves down slope under the influence of its own weight and gravity.

Typically, glaciers exist and form in areas where:
- Mean annual temperatures are close to the freezing point
- Winter precipitation produces significant accumulations of snow
- Temperatures throughout the rest of the year do not result in the complete loss of the previous winter’s snow accumulation
Glaciers are classified by their size (i.e. ice sheet, ice cap,), location (valley glacier, cirque glacier), and thermal regime (i.e., polar vs. temperate).

Significance of Glaciers

Source of freshwater: Glaciers hold 68.7% of the total freshwater found on Earth and can be found primarily in polar regions. These giant masses of ice supply fresh running water to the environment as they slowly melt throughout warmer, dryer seasons. This allows for life to flourish and survive harsh conditions year around.
Ocean Currents: As glacial water melts, its exceptionally cold temperature creates a dense body of water compared to the rest of the ocean. This allows it to sink to the bottom of the sea and travel south. As this happens, the warmer water rises to the top and heads to the poles, primarily the North Pole. This constant movement of water is what brings us ocean currents.
Indicator of climate change: Glaciers are sensitive indicators of changing climate. While other indicators of warming may take time to manifest, the rate of glacial melting highlights the rising average temperature almost immediately.

Impact of Glacial Melting

Overdependence on Rainfall: As a crucial source of freshwater, their disappearance would mean that one would have to be entirely dependent on spot rainfall for freshwater.
Survival of species: The cold water that runs off glaciers keeps downstream water temperatures cooler. This is crucial for many aquatic species as they need cold water temperatures to survive. Glacier loss directly impacts such species, which are an essential part of the food web.
Rising Sea level: As glaciers melt, the water they release adds to the global sea level, which can lead to flooding and erosion of coastal areas.
Loss of cultural identity: Glaciers are part of the region’s cultural identity and for mountaineering and touristic activities. Their loss will surely create an irreversible situation which will have adverse impact of socio-cultural and economic milieu of the region.

For further readings refer:

Melting of glaciers and its impact

Australia’s weather agency issues ‘La Nina watch’

Context: A “La Nina watch” has been issued with some early signs pointing to the weather event that brings rains and floods to Asia, particularly India, forming in the Pacific Ocean later this year by the Australian Bureau of Meteorology (BoM).

El-Nino Southern Oscillation

East-West zonal circulation of tropical winds is an important variant from general atmospheric circulation.
This typical east-west circulation of tropical wind is called Walker Circulation named after a famous scientist G.T. Walker.
Walker circulation is convective cell of air circulation, which is formed due to development of pressure gradient from east to west in the equatorial Pacific Ocean.
After two-three years this general condition of east-west pressure gradient is reversed. i.e. pressure gradient becomes west to east.
- Walker called such oscillations as southern oscillations.

In normal conditions high pressure develops on the sea surface of the equatorial east Pacific Ocean and the western coastal lands of South America due to subsidence of air from above and upwelling of cold oceanic water.
The low pressure is formed in the equatorial western Pacific Ocean due to rise of air from the warm sea surface.
This pressure gradient from east to west generates east-west circulation of trade winds on the surface while there is reverse upper air circulation i.e. from west to east which completes a convective cell.

El Niño:

It is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
El Niño is the “warm phase” of a larger phenomenon called the El Niño-Southern Oscillation (ENSO). La Niña, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the region’s surface waters. El Niño and La Niña are considered the ocean part of ENSO, while the Southern Oscillation is its atmospheric changes.
During El Niño, the trade winds weaken or even reverse:
Instead of blowing from east (South America) to west (Indonesia), they could turn into westerlies.
As the winds blow from the west to east, they cause the masses of warm water to move into the central and eastern equatorial Pacific Ocean.
The rise in SSTs there, thus, produces increased rainfall along western Latin America, the Caribbean, and US Gulf Coast, while depriving Southeast Asia, Australia and India of convective currents.
El Niño occurs simultaneously with the Southern Oscillation. The Southern Oscillation is a change in air pressure over the tropical Pacific Ocean. When coastal waters become warmer in the eastern tropical Pacific (El Niño), the atmospheric pressure above the ocean decreases.
An El Niño event can be identified by the variations in sea surface temperature (SST) over the equatorial Central Pacific.
El Niño events are classified as weak, moderate, strong, and very strong depending on the strength of the positive SST variations.
An El Niño event is announced when monthly Nino 3.4 SST deviations reach +0.50 °C, along with consistent atmospheric features, and when these anomalies persist for three consecutive months.

La Niña:

La Niña basically refers to an abnormal cooling of the central and eastern Pacific Ocean waters off the coasts of Ecuador and Peru.
Such cooling (sea surface temperatures i.e. SSTs falling) is a result of strong trade winds blowing west along the equator, taking warm water from South America towards Asia.
The warming of the western equatorial Pacific, then, leads to increased evaporation and concentrated cloud-formation activity around that region, whose effects may spread to India as well.

Indian monsoon: Indian Ocean Dipole (IOD)

IOD measures differences in sea surface temperatures between the western and eastern parts of the Indian Ocean. It is basically like the El Nino weather system that develops in the Pacific Ocean. It is characterized by an irregular oscillation of sea-surface temperatures in the eastern and western Indian Ocean
Impact on weather patterns: IOD alters the wind, temperature, and rainfall patterns in the Indian Ocean region.
Positive IOD event is known to bring floods to eastern Africa and droughts and bushfires to eastern Asia and Australia. Ex. 2020 Australian Bushfires.
Positive IOD is known to increase the intensity of Monsoon in the Subcontinent and leads to above normal rainfall. A simultaneous occurrence of Positive IOD and El Nino balances the negative impact of El Nino on the Indian Monsoon rainfall. Ex. above normal rainfall in India in 2019.
In contrast, Negative IOD coupled with El – Nino leads to poor Monsoon rainfall. Ex. Deficient rainfall in 1992.

Findings

La Nina Watch Issued: Australian Bureau of Meteorology (BoM) issues a "La Nina watch" indicating potential formation of La Nina later in the year. La Nina brings rains and floods to Asia, especially India.
ENSO-Neutral Conditions: El Nino-Southern Oscillation (ENSO) remains neutral until at least July 2024. Positive Indian Ocean Dipole (IOD) development has stalled.
Current Climate Patterns: ENSO-neutral conditions observed currently. Sea surface temperatures (SSTs) in the central Pacific have been cooling steadily since December 2023.Recent cloud and surface pressure patterns indicate ENSO-neutral conditions.
US Prediction: Transition from El Nino to ENSO-neutral likely in the upcoming month. La Nina may develop with 49% chance in June-August 2024 or 69% chance in July-September 2024, as per the US Climate Prediction Center (CPC).
Global Temperature Trends: Emergence of El Nino in June 2023 resulted in warmest global temperatures for the respective 11 months. Global sea surface temperatures (SSTs) have been recording warm for each month between April 2023 and April 2024.
Indian Ocean Dipole (IOD): IOD currently neutral; recent index value within historically neutral thresholds. Potential positive IOD development stalled; SST observations suggest recent development may have halted. Weaker positive IOD forecast compared to earlier predictions.
Monsoon Booster: Positive IOD can enhance India's southwest monsoon performance. Example: In 2019, a strong IOD event compensated for a 30% rainfall deficit in June.

More solar storms brewing after last week’s aurorae as Sun ‘wakes up’

Context - On Friday night, people from across the world were treated to a rare spectacle: vivid aurorae hanging like curtains of light in the sky. They appeared even in places where aurorae aren’t usually visible. For instance, people at the Indian Astronomical Observatory spotted an aurora over Hanle in Ladakh — far away from places near the poles.

What are Auroras?

Auroras are a natural light display in the sky, predominantly seen in the high-latitude regions (around the Arctic and Antarctic).
It is called aurora borealis or northern lights near the North Pole.
It is called aurora australis or southern lights near the South Pole.

What causes it?

Interaction of charged particles from the sun with the Earth’s atmosphere.
Apart from heat and light, the Sun also releases energetic charged particles. The protective magnetic field around Earth shields us from most of the energy and particles.
However, the Sun does not send the same amount of energy all the time. There is a constant streaming solar wind and there are also solar storms.
During one kind of solar storm called a coronal mass ejection, the Sun ejects a huge bubble of electrified gas that can travel through space at high speeds.
When a solar storm comes toward Earth, some of the energy and small particles can travel down the magnetic field lines at the north and south poles and enter into the Earth’s atmosphere.
There, the particles interact with gases in Earth’s atmosphere and result in beautiful displays of light in the sky.
Oxygen gives off green and red light.
Nitrogen glows blue and purple.

Why are Auroras found only at the Poles?

The reason that the Aurora can only be seen at the poles has to do with how the Earth's magnetic field acts.
The Earth has a metal core and acts much like a bar magnet with two poles and a magnetic field.
Charged particles from the Sun get sucked into the Earth's magnetic field and are then channelled toward the poles, where they are channelled toward a ring around each pole.
The charged particles are trapped in the loops of the magnetic field and are then carried toward the poles.

Deocha Pachami coal mine project

Context: The villagers around the Deocha Pachami proposed coal mining project got an interesting handbill from the Trinamool Congress leadership. The handbill with photograph of Chief Minister Mamata Banerjee says that after the victory in Lok Sabha polls, the Trinamool Congress will ensure a pakka house for the people.

About Deocha Pachami coal mine project

Location - Mohamadbazar Community Development Block of Birbhum district, West Bengal, India.
It is considered to be the largest coal block in the country
- Estimated reserves - around 1,198 million tonnes of coal and 1,400 million cubic metres of basalt
- Geographical area – It spreads over an area of 12.31 sq. km, which is around 3,400 acres.
- Affected Population - There are around 12 villages in the project area with a population of over 21,000, comprising Scheduled Castes and Scheduled Tribes.

Challenges pertaining to Coal Block

Residents V/S Government

Project is facing protests over land acquisition and process involved. About 43% population in the area which falls under the proposed coal mine is inhabited by tribals. Activists insists that under the Forest Right Act,2006 there should be gram sabhas in tribal dominated areas that can only give consent for land acquisition. They allege that the due process has not been followed.
In 2022, the State government announced a revised relief & rehabilitation (R&R) package for those willing to give up land where a person having land in the area will get double its market value along with 100% solatium as land cost ( i.e. around ₹13 lakhs per bigha).
The State government added that one member of every family will be provided job as junior police constable.

Health Issues

Illegal stone quarrying and crushing is being practiced at rampant pace. Doctors in the nearby medical facilities have confirmed the reporting of cases of silicosis in the area.
Experts believe that these cases are under-reported due to pressure from owners of quarries and crushers.

SILICOSIS

Silicosis is a long-term lung disease caused by inhaling large amounts of crystalline silica dust, usually over many years.
Silica is a substance naturally found in certain types of stone, rock, sand and clay. Working with these materials can create a very fine dust that can be easily inhaled.
Once inside the lungs, it causes swelling (inflammation) and gradually leads to areas of hardened and scarred lung tissue (fibrosis). Lung tissue that's scarred in this way doesn't function properly and it becomes a life-threatening disease.

For further reading

Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006 (FRA)

Coal: types, distribution, benefits, challenges, role in industrial location & industrial inertia

Total Solar Eclipse in North America

Context: On April 8,2024 a total solar eclipse will cross North America, passing over Mexico, the United States, and Canada. This type of solar eclipse is a rare event for any particular spot. According to Royal Museums Greenwich, once a place on Earth witnesses a total solar eclipse, it will be about 400 years before that part sees the next one.

Solar Eclipse

A solar eclipse occurs when the Moon moves between the Earth and the Sun, blocking sunlight and casting a shadow on certain parts of the Earth.

Four main types of solar eclipses:

Total Solar Eclipse: When the Moon completely covers the Sun, darkening the sky and revealing the Sun's outer atmosphere, called the corona.
Annular Solar Eclipse: The Moon passes in front of the Sun but doesn't completely cover it, leaving a ring of sunlight visible around the Moon's edges.
Partial Solar Eclipse: When only a part of the Sun is obscured by the Moon, creating a crescent shape.
Hybrid Solar Eclipse: This rare type of eclipse shifts between being total and annular as the Moon's shadow moves across the Earth.

How Often Do Solar Eclipses Occur?

A solar eclipse is witnessed only during the new moon — when the Moon and Sun are aligned on the same side of Earth., which occurs approximately every 29.5 days. However, not every new moon leads to a solar eclipse. They typically occur between two to five times a year.
The reason for their infrequency is due to the alignment of the Earth, Moon, and Sun. The Moon's orbit around the Earth is tilted about five degrees compared to the Earth's orbit around the Sun. This tilt means that most of the time, the Moon's shadow either falls above or below the Earth, missing it entirely.
The points where the Moon's orbit intersects with the Earth's orbit are called nodes. Solar eclipses occur when the new moon aligns with one of these nodes.

Why Are Total Solar Eclipses So Rare?

Despite the potential for multiple solar eclipses each year, total eclipses are exceptionally rare events. A particular location on Earth may only experience a total solar eclipse once every 400 years.
Total eclipses are rare because the Moon's umbral shadow—the dark central portion of its shadow—covers only a small area of the Earth's surface, less than one percent. Additionally, much of the Earth's surface is either uninhabited or covered by water, further limiting the number of people who can witness a total eclipse.
So, while solar eclipses are relatively common, total solar eclipses are extraordinary events that captivate those fortunate enough to witness them, making them a truly rare and awe-inspiring sight.

Taiwan Earthquake: Pacific Ring of Fire

Context: Nine people died, and more than 800 were injured in Taiwan (lies along the Pacific “Ring of Fire”), after the island was struck by its most significant earthquake (7.2 magnitude) in at least 25 years on the morning of April 4th.

About Taiwan earthquake:

Taiwan is prone to earthquakes as it lies along the Pacific “Ring of Fire” where 90% of the world’s earthquakes take place.
Taiwan experiences earthquakes due to the interactions of two tectonic plates the Philippine Sea Plate and the Eurasian Plate.

About Pacific Ring of Fire

It is also known as Ring of Fire, Circum-Pacific Belt, or Girdle of Fire.
It is known as the “Ring of Fire” because of the loop of volcanoes that lies around the Pacific. Around 75 percent of the world's volcanoes are in this area, with a large number of them lying under water.
It is an underwater region on the edges of the Pacific Ocean where numerous earthquakes and volcanic eruptions take place.
It is a U-shaped or semicircle or horse shoe in shape belt of approximately 40,250 kilometers long and 500 kilometers wide, with a chain of over active 450 volcanoes.
Indonesia, New Zealand, Papa New Guinea, Philippines, Japan, United States, Chile, Canada, Guatemala, Russia, Peru, Solomon Islands, Mexico and Antarctica are some countries are some of the important places located in the ring of the fire.

Reason for vulnerability of the Ring of Fire to earthquakes and volcanoes:

The Ring of Fire traces the meeting points of numerous tectonic plates, including the Eurasian, North American, Juan de Fuca, Cocos, Caribbean, Nazca, Antarctic, Indian, Australian, Philippine, and other smaller plates, which all encircle the large Pacific Plate.

The frequent earthquakes and abundant volcanoes along the Ring of Fire result from plate tectonic movement in the region. These tectonic plates end up overlapping at convergent boundaries, referred to as subduction zones.

Earthquakes:

It witnesses so many earthquakes due to constant sliding past, colliding into, or moving above or below each other of the tectonic plates.
As the edges of these plates are quite rough, they get stuck with one another while the rest of the plate keeps moving.
An earthquake occurs when the plate has moved far enough and the edges unstick on one of the faults.

Volcanoes:

The existence of volcanoes in the Ring of Fire is also due to the movement of tectonic plates. Many of the volcanoes have been formed through a process known as subduction. It takes place when two plates collide with each other and the heavier plate is shoved under another, creating a deep trench, like the Mariana Trench, the world’s deepest spot.
Basically, when a ‘down going’ oceanic plate (like the Pacific Plate) is shoved into a hotter mantle plate, it heats up, volatile elements mix, and this produces the magma. The magma then rises up through the overlying plate and spurts out at the surface, which leads to the formation of volcanoes.

Most of the subduction zones on the planet are located in the Ring of Fire and that’s why it hosts a large number of volcanoes.
The volcanoes in Indonesia are among the most active of the Pacific Ring of Fire. They are formed due to subduction zones of three main active tectonic plates, namely the Eurasian Plate, Pacific Plate, and Indo-Australian Plate.

Nickel crashes on 2.5x rise in Indonesian output

Context: Four years ago, Indonesia implemented a permanent ban on nickel ore exports to stimulate foreign investments and promote domestic processing, aiming to bolster downstream industries. This ban attracted significant investment, particularly from China, leading to the construction of smelters and a remarkable 250% increase in Indonesia's nickel production since 2021.

However, this surge in production has resulted in nickel prices plummeting to near three-year lows.

Nickel (Ni)

Nickel is a metallic element with a silvery-white, shiny appearance.
It is the fifth-most common element on earth and occurs extensively in the earth’s crust and core.
Nickel, along with iron, is also a common element in meteorites.
Nickel occurs naturally in soil and water. It is also an essential nutrient for plants.
Ferromagnetic properties of Nickel: Nickel is one of the four elements known to have the property to display ferromagnetism i.e., the ability to form permanent magnets. The others being Iron, Cobalt and Gadolinium.
Production process of Nickel: Nickel does not occur in its native state. Pure Nickel is obtained by reduction of its oxides or by the Mond process which consists of the formation of volatile nickel carbonyl produced by passing carbon monoxide over heated Nickel oxide. This results in the dissociation of Nickel Oxide into Nickel and Carbon Monoxide, which can be used again.
Physical properties of Nickel: Nickel has a high melting point of 1,453 degree Celsius, relatively low thermal and electrical conductivity, high resistance to corrosion & oxidation, excellent strength and toughness at high temperatures and capable of being magnetised.
Chemical properties of Nickel: Pure Nickel is chemically reactive but large pieces are slow to react to a passive layer of Nickel Oxide formed over it.

Minerals of Nickel

Nickel is derived from two types of ore deposits:

Laterites: Principal ore in this class are nickeliferous limonite and garneirite. (Accounting for 54% global Nickel reserves)
Magmatic sulphide nickel deposits: Principal ore in this class is Pentlandite. (Accounting for 35% global reserves)
Hydrothermal systems such as iron-nickel alloy, sedimentary-hosted polymetallic, and volcanogenic massive sulfide deposits, as well as seafloor manganese crusts and nodules. (Accounting for 10% global reserves)

In some cases, Nickel is associated with the Platinum group of elements and copper, which increases the value of nickel ore deposits.

Uses of Nickel

Primarily, world nickel demand is for the production of stainless steel where about 65% nickel is consumed.
Nickel resists corrosion and is used to plate other metals to protect them. It is, however, mainly used in making alloys such as stainless steel. It resists corrosion, even when red hot, so is used in toasters and electric ovens.
A copper-nickel alloy is commonly used in desalination plants, which convert seawater into fresh water. Nickel steel is used for armour plating.
Nickel is used in batteries, including rechargeable nickel-cadmium batteries and nickel-metal hydride batteries used in hybrid vehicles.
Nickel has a long history of being used in coins.

Global Production and exports

World Reserves of Nickel: World reserves of Nickel are estimated at 100 million tonnes with Indonesia and Australia having the highest reserves followed by Brazil and Russia.
World Nickel Mineral Production: The main producers of Nickel mineral in the world are Indonesia (42%), followed by Philippines (14%) and Russia, New Caledonia, Canada & Australia.
Production – Indonesia is the largest producer followed by Philippines and Russia.

Status of Nickel in India

Nickel is not produced from primary sources in the country and the entire demand is met through imports.
Nickel occurs principally as oxides, sulphides and silicates in India.
Important occurrence is nickeliferous limonite in Sukinda Valley, Jajpur district, Odisha.
In addition, nickel is found associated with uranium deposits at Jaduguda, Jharkhand and a process is being developed for its recovery.
The State of Odisha is endowed with the largest share of resources of nickel ore in the country at 175 million tonnes (93%) followed by Jharkhand & Nagaland.
ODISHA - Jajpur (140 million tonnes), Mayurbhanj (27 million tonnes) and Keonjhar (8 million tonnes).
Jharkhand - 9 million tonnes (5%) resources most of which are in Singhbhum (East) district associated with Uranium deposits.
Nagaland - 5 million tonnes (3%) resources which predominantly are in Kiphire district

India will have no option but to depend on imports for this metal till a technology to recover nickel from the overburden of chromite ore in Odisha is established on a commercial scale.

Pancheshwar Multipurpose Project (PMP)

Context: India and Nepal signed an agreement on long term power sharing without making any forward movement on Pancheshwar Multipurpose project.

About Pancheshwar Multipurpose project (PMP):

It is a bi-national hydropower project to be developed on Mahakali River bordering Nepal and India.
Development of PMP is covered under integrated Mahakali Treaty signed between Nepal and India according to which, equal sizes of underground power house i.e. of 3240MV will be constructed on each side of Mahakali river in India and Nepal.
It offers the benefit of regulated water for irrigation to a vast area of agricultural land both in Nepal and India along with the benefit of flood control downstream.

About Mahakali Treaty:

It is an agreement signed in 1996 between the Government of Nepal and the Government of India regarding the development of the watershed of Mahakali River.
It calls for an integrated development of barrage, dams and hydropower for mutual cooperation of the two countries by managing the water resources.
It recognizes the Mahakali River as a boundary river between the two countries.

About Mahakali or Sharda River:

The Sharda River, also called Kali River and Mahakali River, originates at Kalapani in the Himalayas in the Pithoragarh district in Uttarakhand, India.
It flows along Nepal's western border with India.
It joins the Ghaghra River, a tributary of the Ganges.
It takes the name Kali River from the union of the two streams at Gunji as it flows through the hills. After Brahmadev Mandi near Tanakpur, it enters the Terai plains, where it is called the Sharda River.

The mysterious ‘star dunes’

Context: Scientist unveiled the first in depth study of star dune, revealing the internal structure of these geological features and showing how long it took for one of them to form.

Sand Dunes

Sand dunes: deposition occurs due to obstruction to the winds caused by various factors. Depending upon their shape and alignment with respect to wind direction they are classified as:

Barchans: - crescent-shaped sand dune produced by the action of wind predominately from one direction.

One of the most common types of dunes, it occurs in sandy deserts all over the world.
Barchans are convex facing the wind, with the horns of the crescent pointing downwind and marking the lateral advancement of the sand.
These dunes are markedly asymmetrical in cross section, with a gentle slope facing toward the wind and a much steeper slope, known as the slip face, facing away from the wind.

Parabolic dunes: - They are similar to crescentic dunes.

Their shapes are roughly the same, but the slip face of a parabolic dune is on its inward side.
Parabolic dunes are also called blowouts, because winds blow out the center of the dune, leaving just a rim on the outside.

Transverse dunes: - Barchan dunes can become aligned together along a plane perpendicular to the wind. If the line becomes somewhat straight, dune scientists refer to these forward marching ridges as transverse dunes.

They progress forward as their leeward slip faces release sand one avalanche at a time.

Star Dunes

Star dunes are massive sand dunes that owe their name to arms that spread from a central peak.
These sand pyramids, which look like stars when viewed from above, are widespread in modern deserts including sand seas in Africa, Arabia, China, and North America.
Star Dunes are formed in areas with complex wind regime which means wind are blowing from different direction and net sand accumulation, points within the desert where big piles of sand can be blown around to form giant dunes.
It makes up just under 10% of the dunes in Earth’s deserts and are tallest, surpassing other type such as crescent shaped barchan dunes and straight and lengthy linear dunes.

Study Reveals

The study focused upon a star dune in eastern Morocco called Lala Lallia, situated within the Sahara Desert.
The researchers used ground penetrating radar and employed luminescence dating to determine how long Lala Lallia has taken to form, a method based on the energy trapped inside the grains of sand.
It took about 900 years, accumulating roughly 6,400 metric tons annually as wind blows sand through the desert.