Category: Geography Notes PPT

El Nino and La Nina are opposing phases of the El Nino-Southern Oscillation (ENSO) cycle. The ENSO is a periodic climatic trend that involves temperature fluctuations in the eastern and central tropical Pacific Oceans, as well as changes in upper and lower-level wind patterns, sea level pressure, and tropical rainfall patterns over the Pacific basin. The warm phase of ENSO is typically referred to as El Nino, whereas the cold phase is referred to as La Nina. These deviations from average surface temperatures have the potential to have a substantial impact on global weather and climate conditions. 

This article will help you to understand what the La Nina and El Nino phenomena are and how they affect Indian weather.

El Nino Meaning

In Spanish, El Nino means “small boy” or “Christ child”. As it was initially seen by South American fishermen in the early 17th century, the phenomenon was given this name. Seas tended to become warm in the Pacific Ocean around December, which is why the name was picked. El Nino is a large-scale ocean-atmosphere climatic interaction associated with a recurrent increase of sea surface temperatures in the central and east-central Equatorial Pacific. It is linked to high pressure in the western Pacific. The El Nino effect has a negative influence on the Indian monsoons and, as a result, agriculture in India.

According to the work of Sir Gilbert Walker, climate scientists discovered that El Nino and the Southern Oscillation occur at the same time in the 1930s. A variation in air pressure over the tropical Pacific Ocean is known as the Southern Oscillation. The air pressure over the ocean lowers when coastal waters in the eastern tropical Pacific get warmer (El Nino). El Nino-Southern Oscillation is the name given to these two interconnected occurrences by climatologists (ENSO). The words El Nio and ENSO are now used interchangeably by most subject experts.

El Nino’s Impact on India

The pressure distribution in a typical monsoon year (without El Nino) is as follows.

• The pressure along Peru’s coast in South America is higher than in the region bordering northern Australia and South East Asia. 

• As the Indian Ocean is warmer than the surrounding oceans, it has lower pressure. As a result, moisture-laden winds blow from the western Pacific to the Indian Ocean. 

• As the pressure on India’s landmass is lower than that on the Indian Ocean, moisture-laden winds go farther from the ocean to the lands. The monsoons are disturbed if this typical pressure distribution is disrupted for any cause.

El Nino causes the chilly surface water off the Peruvian coast to warm. The regular trade winds are lost or alter their direction when the ocean is warm. As a result, moisture-laden winds from the western Pacific are steered towards Peru’s coast (the region near northern Australia and South East Asia). It creates significant rainfall in Peru, during the El Nino, depriving the Indian subcontinent of its typical monsoon rains. The greater the temperature and pressure differential, the greater is the rainfall deficit in India.

La Nina Meaning

In Spanish, La Nina means “small girl”, and it is also known as El Viejo, or “cold event”. In the Eastern Pacific, the water temperature drops below average. As a result, a powerful high-pressure system has formed over the eastern equatorial Pacific. Low pressure is now present in the Western Pacific and off the coast of Asia. La Nina causes drought in Peru and Ecuador, major floods in Australia, high temperatures in the Western Pacific, Indian Ocean, and off the coast of Somalia, and abundant monsoon rains in India. La Nina conditions are really advantageous to the Indian monsoon. El Nino and La Nina weather patterns occur every 4–5 years on average. El Nino is more common than La Nina. Typically, the episodes last nine to twelve months.

Effects of El Nino and La Nina on Indian Climate

El Nino generates warm weather across the Indian subcontinent in the winter and dry conditions and a deficient monsoon in the summer. In contrast, La Nina causes a better-than-normal monsoon in India. During the El Nino years of 2002 and 2009, India had little rainfall, although the monsoon was typical during the El Nino years of 1994 and 1997. It signifies that India faced droughts during the monsoon for nearly half of the year due to El Nino in the summer. El Nino will harm crops such as paddy, maize, groundnut, guar, castor, tur, moong, and bajra. 

El Nino: Measuring the Effects

Scientists, governments, and non-governmental organizations (NGOs) use a variety of technology, including scientific buoys, to collect data on the El Nino effect. A buoy is a floating object that serves as a navigational aid or warning signal for ships in the middle of the ocean. They are usually brightly coloured (fluorescent). Temperatures, currents, winds, and humidity are all measured by these buoys. The buoys provide data to academics and forecasters all across the world on a regular basis, allowing scientists to more correctly anticipate El Nino and visualize its evolution and influence around the planet.

The Oceanic Nino Index (ONI) is a tool for determining how much sea surface temperatures have deviated from normal. The major tool for determining, assessing, and forecasting each El Nino event is the Oceanic Nino Index, which is a measure of the departure from normal sea surface temperature in the east-central Pacific Ocean. El Nino occurrences range in severity from mild temperature rises (about 4-5° F) with relatively little local effects on weather and climate to extremely severe increases (14-18° F) linked to global climate change.

You must have seen mountains and different kinds of patterns in them. Sometimes wave-like pattern or sometimes V-shaped or zig-zag patterns as well. These patterns are called folds which are formed because of bending due to some stress. There can be 2 fold, 3 fold, four-fold, or multifold in the mountains and these folds form different patterns. In this article, we will be talking about folds, it’s meaning or factors responsible for folds, types of folds, etc. 

What is Fold?

It is a structure of wave-like pattern which is formed by bending of the rocks instead of breaking under any compression. These waves can be seen in stratified rocks which were formed because of sedimentary deposits on the flat horizontal sheets. These horizontal sheets are no longer flat at some places and have been warped with time. Sometimes warping can be seen in the rocks as the appearance of the structure changes and sometimes the warping is so much that two layers become parallel to each other. The rocks fold in and fold down and form a pattern. 

The size of these folds can be varied. Somewhere they can be hundreds to thousands of kilometres and somewhere they can be only of few centimetres or even less. Sometimes there can be seven fold or 10 fold mountains or even more. The size and number of folds can be varied.

The classification of various folds depends upon the appearance and attitude of their axes. The axial plane can be horizontal, vertical, or inclined and it divides the fold symmetrically as possible. An axis is the point of intersection of the axial plane with one of the starta. The Important two-fold which we usually see in the mountains are anticline and syncline. One fold is convex-shaped upwards and another has downwards.  

Factors Responsible for Folds

Following are the factors which can lead to the classification of folds:

It depends upon the tightness of the folding of the layers as shown in the figure below. It can be open, tight, or isoclinal.

• Orientation of the Axial Plane

Relative to the horizontal plane along with the orientation of gold limbs, the orientation of the axial plane also leads to different kinds of folds which can be seen in the diagram below. It can be upright, overturned, or recumbent. You clearly can see the difference in folding between all of them in the diagram.

It depends on the thickness of the folded beds as well. The thick beds form concentric folds whereas thin beds form a foliation parallel to the axial plane.

Types of Folds

Anticline: 

It has an arc-like shape and its core has the oldest beds. The layers of the rocks become older towards the centre and they are more convex upwards.

Syncline: 

It is the opposite of anticline. It is a fold that is convex downwards which is also termed as synformal syncline and has younger rocks at the centre. Some synclines can point upwards due to overturned or formation of an anti-formal syncline.

Symmetrical: 

If the axial plane is vertical, then it is a symmetrical fold.

Asymmetrical: 

if the axial plane is not vertical but inclined, then it is an asymmetrical fold.

Isoclinal: 

these are those kinds of folds in which limbs are parallel to each other and approximately to the axial plane as well. 

Overturned: 

When the folds are highly inclined they are called overturned or overfold.

Monoclines: 

These are kind of folds in which all the layers incline in one and same direction.

Chevron: 

In chevron, folds look like zig-zag and it has repeated patterns with straight limbs and sharp hinges. They formed V-shaped beds which are formed of regional compressive stress.

Slump: 

It is a fold that is formed because of a landslide where sediments were softer. It forms during sedimentation or lithification. 

Ptygmatic: 

It is a type of slump fold where the material which is folding is more vicious than the surrounding material. These are random and disconnected.

Disharmonic: 

These folds are those in which different layers are having different kinds of folds. There can be a combination of various kinds of folds.

Fold Mountains

On the nature of folds, mountains can be divided into two parts which are mentioned below:

These are said to be the mountains with open folds where patterns of anticlines and synclines can be found and have wave-like patterns. 

These are those mountains in which rock strata are compressed so much that it forms a complex pattern.

Features of Fold Mountains

• These are said to be the most widespread as well as important mountains in the world.

• They are young mountains.

• They can extend up to a great length but they have a small width.

• These are great sources of minerals as well such as tin, copper, gold, etc.

• They are mostly found in the margins of a continent and ocean.

• Fossils here suggest that sedimentary rocks were formed because of the accumulation and consolidation of sediments and silts in the marine environment.

• Usually, they have both concave and convex types of slopes.

A landform created due to the movement of glaciers (flowing ice)  is called a glacial landform. Glaciers are huge bodies of ice that flow in water and glacial movements and erosions lead to the formation of various landforms. These huge chunks of ice and meltwater erode striate, and polish rocks, and are potential weathering agents. Fjords, U-shaped valleys, cirque landform, horns, hanging valleys, moraines, glacial erratics, paternoster lakes, glacial till and flour, kettles, are some of the landforms created by glaciers.   

Glacial landforms are common in higher mountain ranges, regions of Greenland, and Antarctica. Nearly 30 percent of our planet was covered with ice in the ice-ages. Due to climate change, the ice started to melt and glaciers led to the formation of various landforms. The regions that were once glaciated, now house most of the glacial landforms. Periglacial landforms are also formed in the cold climate. 

Types of Glaciers

The common types of glaciers are ice sheets or ice caps, continental glaciers, mountains or valleys, outlet glaciers. The ice sheets are way bigger as compared to the valley glaciers. The ice sheets bury their underlying landscape and are formed continuously over extensive areas. The flow of the continental ice sheets is from the center to the outward direction. Valley glaciers can be characterized by ice chunks flowing like a river, and are usually found in the mountains. The flow of these valley glaciers is entirely dependent upon the regional relief features. The glacial landforms formed due to the actions of valley glacier systems and continental ice sheets are often similar by their outward appearance but differ in magnitude.     

Periglacial Landforms

The term periglacial means ‘near glacial’, and the periglacial regions are either adjacent to or very close to the glacial regions. However, these regions are beyond the glacial limit and lie in a zone of the freeze-thaw cycle. These regions are characterized by periglacial landforms. 

The freeze-thaw cycle is caused due to the unique anomalous expansion of water. On freezing water changes its state from liquid to solid and expands in volume by nearly 9 percent. In periglacial regions, freezing of water into ice is often accompanied by differential ice growth. In this process, the air is trapped along with water, leading to a greater increase in the volume of ice. Such air and water mixture can exert a pressure of about 200,000 kilopascals, which is sufficient to break the rock, enclosing it. Hence, when water is enclosed in a crack or pore of a rock, it can be a potential agent of weathering. Multiple such cycles of freeze and thaw lead to the formation of ice crystal fractures. In this process, weathering is propelled by frost-shattering and frost-heaving. Furthermore, perennial ice landforms can be observed in the permafrost areas, wherein the ground is frozen throughout the year.  

 

Glacial Erosion Features

The temperature changes in glacial ice determine the rate of glacial erosion. Basal sliding and internal deformation are the two processes that bring about the movement of glaciers under the influence of the earth’s gravitational force. To understand the glacial erosion features, let us go through the classification of glaciers into temperate glaciers and polar glaciers. 

Temperate Glaciers: These are also referred to as isothermal glaciers. These glaciers have a constant temperature throughout their masses. This temperature is referred to as the pressure-melting point. It is equivalent to the melting point of ice at a given pressure. 

Polar Glaciers: On the other hand, the polar glaciers have a temperature that is lower than the pressure-melting point. 

Subpolar Glaciers: The subpolar glaciers are slightly different from the temperate glaciers, they exhibit an intermediate thermal nature. The temperature at the margins of these glaciers is very low whereas their interior parts exhibit temperate nature. 

Internal Deformation: The two factors that bring about internal deformation of glaciers are shear stress due to the glacial ice and the slope of the glacial surface. When the weight of ice in a glacier becomes too large to be withstood by its shape while moving in the water, it results in shear stress. The steeper the slope of the glaciers, the greater the strain is created due to its weight. The movement of the ice crystals within the glaciers and the brittle fracture caused under tension affect the rate of internal deformation. Also, the temperature of the glacial ice determines the amount of strain and the subsequent deformation in the glacier. Hence, these brittle fractures are more evident in polar ice than in temperate ice.

                 

Basal Sliding

Basal sliding is one of the main factors that lead to glacial erosion. The temperature at a glacier’s base plays an important role in determining the rate of erosion of its bed. Basal sliding is the ability of a glacier to slide upon its bed. It is restrained when the temperature of the glacial base is lower than the pressure-melting point. The low basal temperature propels the adhesion of the glacier’s base to the frozen bed. 

The rate of basal sliding is quite low in polar glaciers because they are more rigid. This, in turn, diminishes the ability of the polar ice glaciers to creep, and erode by basal sliding. Consequently, polar glaciers have a very slow rate of erosion and mostly they erode due to internal deformation. Hence, less volume of meltwater, sediments, and less number of glacial erosional landforms are formed from polar glaciers. 

On the other hand, in temperate glaciers erosion occurs mostly by basal sliding. The temperate glaciers have a layer of rock debris at their base. This layer may have a thickness of some centimeters to few meters. Since the ice in the temperate glaciers is not as rigid as that in the polar glaciers, basal sliding is more likely to occur in them. The base of temperate glaciers is like a sheet of sandpaper, wherein ice and rock debris form the base layers. The capacity of bearing shear strain is low in these glaciers. The rock debris and ice base make it more conducive for temperate glaciers to erode and form various glacial erosion landforms. 

Quarrying is another important glacial erosion feature or process. In this process, the big rock particles are eroded away from the base of glaciers, when they are subjected to differential stress, high-stress gradients, or temperature fluctuations.      

Glacial Depositional Landforms

The rock debris carried along with the glacial ice is deposited at the glacial margins. It is also deposited at the sites where the velocity of the glacial ice is the lowest. A meltwater deposit is referred to as outwash and is likely to be formed in front of the glacial margins, in channels under the glaciers, or in lakes beneath the glaciers. An outwash is usually bedded, and the layers of rocks in an outwash are well sorted as per the grain size. On the other hand, when the debris is deposited by the glacial ice directly, the glacial depositional landforms so formed are called tills. The common types of tills are melt-out till, lodgement till, ablation till. 

Glacial Erosion Landforms

There are two main processes that cause glacial erosion, plucking, and abrasion. When the rock debris at the base of the glacier ice is subjected to constant grinding, a fine abrasive agent called rock flour is obtained. These particles polish rock surfaces by making fine scratches and often renders the rock surfaces highly lustrous. Striations, p-forms, and grooves are among the other features of glacial erosion. These are the tools of abrasions and the scratches they make on the rock surfaces shape the glacial erosional landforms.  The common types of glacial erosion landforms of valley glaciers are discussed below.

Cirque Landform

A cirque resembles the shape of an amphitheater. Cirques are bowl-shaped depressions that are carved out due to the glacial movements. The hollow-end of a cirque is faced towards the down-valley. The back of the cirque landform is called the headwall and is formed by a curved or bow-shaped cliff. Mostly the headwall makes a semi-circular back in the cirques that are cut into flat-topped plateaus. Otherwise, due to height irregularities along the perimeters of a cirque landform, the headwalls are formed in an angular shape. Often, cirques are characterized by shallow basins leading to lakes at their bases. By closely examining the shallow basin of a cirque and the headwall of an adjoining cirque, signs of substantial glacial abrasion and plucking can be observed. 

Cirques are formed when the headwall above the glaciers is subjected to ice wedging and frost shattering. The debris is deposited either on the surface of the glacier or into the cracks between the cirque headwall and the glacier top. The debris deposited on the surface of the glacier gets buried in ice and is eventually moved to the glacial base. Gradually, this rock debris aids in glacial erosion and polishes the headwall’s base and the cirque bottom.  

Tarns

The lakes contained in the over-deepened basins of cirques are called tarns. Often, at the initial and final stages of growth and retreat of valley glaciers, there is no ice beyond the cirques. These types of glaciers mainly lead to the formation of cirque basins and bedrock bottoms of cirques.  

U-Shaped Valleys, and Horns

Meltwater stream valleys are unlike valley glaciers. In the stream valleys, the eroded debris falling off the headwalls and sidewalls of the glaciated valleys are washed off with the glacial ice. However, the glaciers move along quite a large area of cross-section of the valleys as compared to the streams. Therefore, the meltwater streams erode a slimmer area of valleys, unlike the glaciers that erode the valley bases. Usually, the meltwater streams erode strips of rock at the lowest part of valleys and carve out V-shaped valleys. When the glaciers come in contact with the V-shaped valleys, the loose debris from the base and the sidewalls are removed. Also, glaciers further erode the sidewalls and base of the valleys, forming U-shaped valleys. The U-shaped valleys are characterized by flatter bases and steeper sidewalls.

Aretes and Horns

Aretes are glacial formations that are often found between two circles facing opposite each other. These are knife-edged ridges formed by the glacial erosion of the U-shaped valleys. The bedrock bottoms of these valleys are further eroded by the glaciers, due to which the upper reaches of the parallel valleys are reduced to aretes. In aretes between two cirques, there is often a low spot, referred to as a col. 

Often on the flanks of higher mountain ranges like the Alps, several cirques are arranged radially. When the upper parts of these mountain ranges are eroded by glaciers, a sharp peak is formed. These sharp peaks are called horns and are surrounded by steep headwall cliffs separated by aretes.

Glacial Depositional Landforms

The common types of glacial depositional landforms are moraines and flutes. 

Moraine

Loose rock debris is collected and transported along glacial ice when a glacier moves by the walls and bed of a valley. As a glacier moves down its path, the collected rock debris gets accumulated along its lower margins. The rock debris eventually gets deposited in front of the glacier, as the glacial ice melts away. Also, the loose debris brought down by other tributary valleys that are non-glaciated gets mixed up with the debris deposited by the glaciers. These deposits of debris form a snout at the mouth of the glacier. These debris snouts or tills melted out from glaciers pile up into ridges are termed moraines. The moraines that are formed at the lower ends of glaciers or right in front of the glaciers are termed as end moraines. The moraines that are formed beside the margins of glaciers along the slopes of valleys are termed lateral moraines. Terminal moraines and recessional moraines are some of the other types of moraines formed by glaciers.  

Flutes 

Some glaciers have so much debris accumulated beneath the ice, that the glaciers slide upon the bed of a muddy till. Cavities are carved out when a glacier moves along, and the basal ice flows around a debris knob at the bed of the glacier. The muddy paste of loose rock debris flowing under a glacier can be deposited in these cavities in the shape of a tail. These tail-like elongated deposits of till are called flutes. These glacial depositional landforms may vary from several centimeters to meters in height, and from centimeters to kilometers in length. Mostly, continental ice sheet glaciers tend to form large flutes. 

A Category of silicate mineral, Hornblende is a crucial element of the amphibole group of complex silicates in which the tetrahedra are associated to form an ongoing chain twice the width of the pyroxene chains. The hornblende rock is often found in igneous and metamorphic rocks.

Discovery – Who Discovered Hornblende?

The name Hornblende was originally given in 1789 by Abraham Gottlieb Werner.

So what does the name mean?

Etymology

The name hornblende is derived from German words horn and blenden which refers to its similarity in appearance to the metal-bearing mineral ores.

Chemical Formula of Hornblende Mineral

Hornblende chemical formula is as given: (Ca,Na)2-3(Mg,Fe,Al)5(Si,Al)8O22(OH,F)2

These constituents can be present in different amounts. Thus it is notable that the hornblende mineral has a varied composition. There are different varieties with similar physical properties which can only be differentiated in the laboratories

Let us look further into the chemical nature of the mineral.

Chemical Composition of Hornblende

It is an isomorphous mixture of three molecules and the hornblende chemical composition is as stated:

These minerals are difficult to distinguish by physical means. The iron, magnesium, and aluminum ions can freely provide the alternative for each other and form what has been distinctive as separate minerals. The minerals are assigned the names Magnesio-hornblende, Ferrohornblende, Aluminio-ferro-hornblende and Aluminum-magnesio-hornblende.

Sodium, potassium are often present. Manganese and titanium can also be present. In crystalline structures, fluoride is more common than hydroxide.

Occurrence – Where Do You Find Hornblende?

This element of silicate mineral is a key constituent of igneous and metamorphic rocks. Recall what are they?

Hornblende has rock-forming properties. It forms both igneous and metamorphic rocks.

Igneous Rocks – These rocks, also known as the magmatic rock, are formed by the cooling and solidification of the lava or the magma. Hornblende is present in acidic and intermediate igneous rocks.

Example – granite, diorite, syenite, gabbro

Metamorphic Rocks – These are rocks formed from some other type of previously present rocks. They are formed due to factors such as extreme pressures, temperature, or a mixture of both.

Hornblende also forms metamorphic rocks. Examples- Gneiss, schist

Edenite is a rare variety of hornblende that has 5% iron oxide and thus appears white to gray.

Hornblende Properties

Let us further look into the physical and chemical properties of hornblende.

Category – Silicate mineral; inosilicates; amphibole group

Physical Properties

Mohs hardness- 5-6 ( Mohs scale 1 is talc, while 10 is for diamond)

Specific gravity – 2.9-3.4

Transparency – Opaque

Color – green. Greenish-brown, black

Luster – vitreous, dull, submetallic

Streak – pale gray, gray-white, colorless

Tenacity- brittle

Chemical Properties

Diagnostic Properties – Cleavage (intersect at 124-56 degrees), color

Hornblende thin section in PPL ( plane-polarized light) image ranges from green to dark brown.

Isotropy/Anisotropy – Anisotropic i.e. it shows different properties when observed in different planes and axes.

Crystal- monoclinic.

Further details about the crystal form of hornblende are mentioned below.

Hornblende Crystal

As mentioned above, it is a monoclinic type of crystal. These are prismatic crystals with a diamond-shaped cross-section. It is rarely found as an individual crystal, instead always as platy or grainy crystals.

Hornblende Thin Section

Hornblende thin section in PPL (plane-polarized light) image ranges from green to dark brown.

Green Varieties have

• X= light yellow-green

• Y=green or grey-green

• Z=dark green.

Brownish Varieties have

 Geographical Locations

Hornblende is a commonly occurring mineral but only specific places harbor good quality crystals. A lot of the Lustrous, well-formed crystals, mostly as microcrystals, come from –

• The Italian volcanoes at Monte Somma, Vesuvius

• The Montenero Quarry, Latera, Lazio Province

Exceptional Crystals in Relatively Large Prismatic Crystals Come From –

• Studsdalen, near Kragero, Telemark, Norway.

• Arendal, Langesund Fjord

• Risor, Aust-Agder.

Dark green Hornblende was found in Malmberget, Gällivare, Sweden; and doubly terminated floater crystals come from Žim (Schima), Teplice, Bohemia, in the Czech Republic.

In the U.S, crystal plates have come from the iron mines in the Jersey Highlands in Bergen, Passaic, and Sussex Counties, New Jersey. Good Hornblende crystals also come from upstate New York regions in St. Lawrence Co. at Edwards, Pierrepont, Gouverneur, and Russel. In Canada, well-formed stubby crystals come from Bancroft, Ontario; and at the Bear Lake Diggings in Gooderham,Haliburton Co., Ontario.

Conclusion

Thus it is an important mineral ore that forms a constituent of various rocks used for day-to-day purposes.

India has the 7th largest area and the 2nd highest population in the world. India is the perfect example of diverse topography. It has excellent examples of beautiful land formations giving it a variety of vegetation, people, culture, and wildlife. Our country India has a diverse culture. Let us learn how many physical divisions are there in India with a proper description of its location and neighbouring countries surrounding it. In this section, you will find a proper description of the topics mentioned here.

India: A Brief Introduction

Many travellers visited different eras of history and depicted India as a diverse country where people consider guests as gods and believe in harmony. India has always been the prime attraction for other countries. Spreading across an area of 3.287 million square kilometers, this country is the home of a diverse ecosystem comprising exotic wildlife and vegetation.

Where is Our Country Located?

Our country India is located in the northern hemisphere spreading from the latitudes  37°6’N to 8°4’N. It has a span ranging from the longitudes 68°7’E to 97°25’E. The Tropic of Cancer (23°30’N) passes through the upper middle section of the subcontinent dividing it into two parts. The majority of this country enjoys a tropical and subtropical climate.

Due to the vast longitudinal distance, India has a difference in time witnessed by different zones. For instance, Arunachal Pradesh witnesses sunrise two hours before it hits Kutch in Gujarat. Despite the fact, the Indian Standard Time is considered to be 82°30’E longitude.

Administration and Neighbours

If you want to find out which is our country on the map, you can easily tell it by pointing at the neighbouring countries surrounding India in the eastern, northern, and western parts. The border of our country is shared by seven other countries that we call neighbours. These countries are Sri Lanka, Bangladesh, Myanmar, Bhutan, Nepal, China, and Pakistan.

India has 29 states as per the new configuration and 7 union territories. The capital of our country is Delhi. The central government takes care of the international affairs whereas the state governments take care of the individual states. Every state is divided into smaller sections called districts for better administration. Rajasthan is the largest state in India by area whereas Goa is the smallest state. Rajasthan is also bordered by Pakistan on the western side. If you study the map carefully, you will understand India’s physical and adjacent countries.

Physical Divisions of India

The geographical map of India is topographically divided into the following sections. This is the part where you will find the answer to ‘how many physical divisions are there in India?’

1. The Himalayan Ranges

The mighty Himalayan Ranges guards the northern and north-eastern border of India like a giant. This is the highest mountain range in the world. Our nation India is guarded against the Arctic winds by this huge wall so that the majority of the states can enjoy a subtropical climate. The ranges are divided into three parallel sub-ranges.

• The Greater Himalayas, also called Himadri, is the highest in the world.

• The Middle Himalayan ranges or Himachal.

• The Southern Himalayas or the Shivalik Ranges.

A majority of the highest peaks in the world are located in the Himalayas.

2. The Northern Plains

The Northern Plains are a prime division of India that comprises the river basins and plains. It includes the network of a few of the largest rivers in the world such as the Ganges, Brahmaputra, and Indus. The river basins are rich in alluvial soil and provide the ideal place for human settlement. This is why this physical region of India is highly populated. Cultivation and industries are the prime occupations of the people here.

3. The Great Indian Desert

You will easily answer which is your country when it gives the hint of the Thar Desert. It is the desert region located in the western part of our country and is considered to be one of the diverse landscapes. It sprawls over Rajasthan and a part of Gujarat. Due to the arid climate and less vegetation, the human population here is also less.

4. The Peninsular Plateau

This is probably the vastest physical division of India that sprawls across the lower northern states to the peninsular region. This area covers a few of the oldest mountain ranges in the world. Aravalli Hills resides on the north-western corridor of this division. Satpura and Vindhya mountains are also in this region. The eastern and western borders of this region are guarded by the Eastern and Western Ghats respectively.

5.  Coastal Plains

This is the longest among the physical divisions of India. India boasts of its 7516 km of continuous coastline adding more diversity to its topographical map. The eastern coastline is guarded by the Bay of Bengal. The western part is guarded by the Arabian Sea and the southern part faces the Indian Ocean. This region is adorned by fertile deltaic formations in the estuaries of large rivers such as the Ganges and Brahmaputra.

6.  Archipelagos

The presence of two archipelagos explains India is which type of country. In the south-eastern part of the subcontinent, Andaman & Nicobar Islands lies. In the south-western part, we find the Lakshadweep in the Arabian Sea.

You can now easily find out in which region India is located. Study this article properly to gather more knowledge about India and its different physical divisions.

Our planet Earth is very diverse in nature. There are regions that are completely distinct in terms of their various features such as geographical conditions, weather, etc. It is due to these distinct geographical conditions that play a major role in the presence of different types of climates that persist all over the world. 

There are various climates in our world, which are what prevail in a specific region for a longer period of time. Now, when we talk about the types of climates, there are majorly two. One is Tropical and another is Temperate. 

Here, you can get to learn about the climate classification which is given by famous Climatologist Koppen. You will get to learn a lot in detail about the climate. There are also some of the many features of the climate types. People can also learn more about the classification of climate through charts, world maps, and tables. 

Koppen Classification of Climate

Wladimir Köppen (1846 – 1940), born in Russia, was a great German Climatologist as well as an amateur botanist. He gave a detailed climate classification and his first-ever classification came in 1918 and continued to refine and modify it. The last modified version of his classification was published in 1936. This classification was done with the usage of different kinds of symbols which represent different meanings and climates. Majorly, the climate classification was done into five major groups along with one more type which was considered a special category.

The five major climate groups are represented by capital letters i.e. A, B, C, D, and E. Among these major groups, only B belongs to the dry type of climate whereas others are humid climate groups. These major groups are further divided into subtypes on the basis of their features like temperature and precipitation or level of dryness or coldness, etc. 

Symbol ‘a’ means hot summer in which average temperature is above 22°C, ‘c’ refers to cool summer where the average temperature is below 22°C, ‘f’ means no dry season, ‘w’ represents a dry season in winters and ‘s’ represents a dry season in summer, ‘g’ refers to Ganges’ type of temperature of annual march when the hottest month comes before the Solstice as well as the summer rainfall, ‘h’ means where the annual average temperature is less than 18°C, and ‘m’ means monsoon. Besides these, Capital ‘S’ and ‘W’ are used for the further classification of the dry season in which ‘S’ means semi-arid regions or steppe whereas ‘W’ represents arid or desert regions. For further division of polar climate, capital ‘T’ and ‘F’ symbols are used. In which ‘T’ means Tundra and ‘F’ means Icecap. Besides all these, Capital ‘H’ represents the highlands.

Koppen Climate Map

Here in this world map, you can see the distribution of different types of climate as per Koppen Climate Classification.

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The detailed classification of different kinds of climate is mentioned below in the table.

Climate Classification Chart

A. Tropical Moist Climates

• Different kinds of sub climates can be found under this category such as Af, Am, and Aw.

• This type of climate can be found in 15° to 25° in the north and south of the equator. 

• In this type of climate, the temperature always remains above 18°C.

• The annual precipitation here is generally above 1500 mm.

• Af represents the Tropical wet Climate. Here, in tropical regions usually, the tropical climate is there along with precipitation all year round. Monthly variations in temperature of around or less than 3°C can be seen. Here, extreme high humidity is found along with cumulus and cumulonimbus clouds which form every day which leads to high precipitation.

• Am represents the Tropical monsoon climate. Here, annual precipitation is much similar to that of Af, but mostly occurs within 7 to 9 of the warmest months and the rest of the years usually less rainfall occurs here.

• Aw represents Tropical wet and dry climate or we can say Savannah type of climate. Extended dry season can be seen in the winters whereas, in the wet season, precipitation occurs less than 1000 mm and usually in the summers.

B. Dry Climates

• This type of climate is more dependent upon the nature of the precipitation rather than the temperature and here evaporation, as well as transpiration, exceeds the total precipitation.

• This type of climate can be found in the range of 20° to 35° from the north and south of the equator.

• It has further four subdivisions as BSh, BWh, BSk, and BWk. Basically, two major types here are BS and BW. Only ‘k’ and ‘h’ are suffixed attached to define the aridness or location.

• BW is a dry arid climate and is considered the true desert climate which covers about 12% of the total land of the Earth.

• BS represents the semi-arid type of climate which are grasslands regions and which covers almost 14% of the land of the Earth. These regions receive more rainfall than the BW type of climatic regions.

C. Moist SubTropical Mid-latitude Climate

• In simple words, we can say that these are warm temperate climate regions where warm and humid summer and mild winters can be seen.

• This type of climate can be found in the ranges of 30° to 50° in the north and south of the Equator and mainly can be found at the eastern or western sides of the continents.

• Convective thunderstorms can be seen in the summertime whereas mid-latitude cyclones can be seen in the winters.

• It can also be sub-classified into various categories. 

• Cfa is a humid subtropical climate where hot and humid summers can be found with thunderstorms whereas winters are mild and precipitation usually occurs because of the cyclones.

• Cfb is an example of marine climate that is found on the western edges or coasts of the continents. Here, hot and dry summer can be found with largely humid conditions whereas winters are mild with heavy precipitation.

• Cs is an example of a Mediterranean type of climate where precipitation usually occurs in winters because of mid-latitude cyclones.

D. Moist Continental Mid-latitude Climates

• In this type of climate, summers are usually warm but also can be cool whereas winters are usually cold.

• This type of climate can be found towards the poles or at the subtropical mid-latitude climates or C-climates.

• The average temperature is only above 10°C during the warmest months whereas, in coldest months, it can be less than minus 3° C.

• Here, winters are very cold along with strong winds as well as snowstorms that come from the Continental polar regions or the Arctic air masses.

• It has also further subdivisions which include major three types i.e. Dw which means dry winters, Ds which means dry summers, and Df represents precipitation all around the year.

E. Polar Climate

• Here, in these types of climatic regions, the temperature is too low.

• Even, in the warmest months of the year as well, the temperature is less than 10°C. 

• It usually occurs in the coastal areas of the northern regions of Asia, North America, Europe, Greenland, and Antarctica.

• It is also further divided into various types such as ET and EF. ET refers to Polar Tundra where the soil in the form of permafrost can be seen and EF refers to Polar Ice Caps that are permanently frozen.

There are various merits and demerits for the Koppen Climate Classification System. So first, let us take look at the merits of it.

Merits

There are numerous merits of the Koppen climate classification system, out of which some are mentioned below:

• The Koppen climate structure is quantitative in nature along with its division.

• The system is basically one that is quite easy to understand. 

• One can measure the Koppen climate classification system in an easy manner as well.

• The Koppen climate classification system coincides with the vegetation pattern that is found in any region.

• The Koppen climate classification system has importance pertaining to two major factors, which are temperature and precipitation.

• The Koppen climate classification system is very vast, so much so that it actually covers all the types of climate patterns as well as conditions that are found on the Earth.

Demerits

You must be aware of the saying – Every coin has two sides. It is true in terms of concepts relating to the Koppen climate classification system as well.  And so, here are a few of the demerits that you must be aware of:

• The concept is quite vast and has various classifications which might get difficult to memorize at times.

• The Koppen climate classification system is majorly based on the average values. This pertains to the fact that one needs average values of temperature and precipitation in order to make use of it. You may already know how precipitation is much more of an aspect that is estimated rather than measured. So, such average values are, on occasions, difficult when it comes to comparisons and yielding the desired results.

• The Koppen climate classification system ignores various features. These include the intensity of the precipitation, number of rainy days, cloud coverage, variations in temperature or precipitation, and much more.

• In this system of Koppen climate classification, Koppen also ignored the air masses and their significance in the climate formation that contribute a lot in Climatology.