Geography

• The Monsoon is traditionally defined as the seasonal reversal of winds and related changes in precipitation. Monsoon is a surface wind that blows in a particular direction in one season but reverses completely in the other season.
• Monsoon is the main characteristic of the Indian Climate and requires special study. Hence, we will study that in detail.

Mechanism of  summer Monsoon

• During summer, interior parts of the North Indian Plains covering Rajasthan, Punjab, Haryana etc., are heated strongly. As a result, low pressure develops, resulting in the formation of the monsoonal trough.
• Temperature over the Indian Ocean is still low. Hence, high pressure prevails over the Indian Ocean.
• Hence, the general movement of air in JUNE is from the South-West (Indian ocean) to North-East (Indian Subcontinent) (this direction is directly opposite to trade winds prevailing during Winter).
• When these moist winds from the Indian Ocean pass over Indian Subcontinent, they cause widespread Monsoon from June to September.

Winter Monsoon

• During Winter, high pressure is developed over land, whereas low pressure prevails over oceans. Hence, winds start to blow from North-East towards South-West (North East Trade Winds).
• These are dry & cold winds causing no rainfall except on the Coromandal Coast, where it gathers moisture after passing over the Bay of Bengal.

Shortfalls

• But this presents a very simple picture and fails to explain the following:-
  • Why low-pressure areas on land are not stationary & suddenly change their location?
  • Why are there no anti-monsoon circulations in the upper-troposphere which must be there if they were thermally induced?
  • Low pressure in Northern India develops in April & May, but rain starts there in June. Why??
• Monsoon rains are an amalgamation of convectional, orographic & cyclonic rainfall & the thermal concept fails to explain this.

• When there are summers in the North Hemisphere, there are winters in the Southern Hemisphere. As a result, a High-pressure zone develops near a small island in the Southern Hemisphere in the South Indian Ocean called Mascarene. Winds from this high-pressure area, termed as Mascarene High by scientists, start blowing towards low-pressure areas in the Northern Hemisphere, along the east Somalia coast.
• The strength of Mascarene High is a crucial factor in determining the intensity of the Monsoon in India. Stronger is the Mascarene High, stronger will be the push caused by them and stronger will be the rainfall over Indian Subcontinent.

• The monsoon wind that is deflected to the east as it crosses the Equator (due to Coriolis Force) is further deflected to the east by the mountains of Africa on the Somalian Coast and Somali Jet. The Somali Jet transits Kenya and Somalia and exits the African coast at 9 degrees north at a low altitude at very high speed.
• Hence, it gives a strong push to the Monsoon winds & also deflects them towards India.

(This Jetstream was discovered by J. Findlater, a British meteorologist & it is most pronounced between 1.0 and 1.5 km above the ground.)

India is under the influence of Sub-Tropical Westerly Jet (STWJ). It impacts the Monsoon in the following ways

1. Winters

• Due to the sun’s southward apparent movement during winters, all the earth’s pressure belts move southwards. As a result, STWJ also moves southwards & comes over North India (from the Himalayas).
• These Jet streams create High-Pressure Zone over North India, so no rainfall occurs during Winter. 

2. Summers

2.1 Early Summer

• With the onset of summers, the sun starts to move northwards; as a result, pressure belts of the earth, along with STWJ, also starts to move northwards. 
• During early summers, half of the STWJ is over the Northern plains, while the other half moves north of the Himalayas. Hence, high pressure continues to be maintained over Northern India. Until the whole of STWJ doesn’t move out of North India, Monsoon cant strike Indian Subcontinent. 

2.2 Late summer, near June

• During late summer, STWJ entirely moves north of the Himalayas, and low pressure develops over North India. Hence, Monsoon strikes Indian Subcontinent in June.

• El Nino creates High Pressure near Northern Australia & as a result, Walker Cell between Western Pacific Pool (WPP) and the Western Indian Ocean (Mascarene High) is altered. In normal conditions, this Walker Cell helps to strengthen the High Pressure in the Western Indian Ocean. But during El Nino, Mascarene High is not strengthened.
• As Mascarene High helps push monsoon winds towards India, in case of weak Mascarene High during El-Nino years, the push would be weaker, resulting in lower rainfall in Indian Subcontinent. 

La Nina

• La Niña is the reverse of the El-Nino. Here, extreme Low Pressure prevails over Northern Australia. It strengthens the Mascarene High more than what happens in normal conditions.
• La Niña years are infamous for frequent and intense hurricanes and cyclones in the Atlantic Ocean and the Bay of Bengal, likely due to multiple aiding factors, including high relative moisture and relatively low wind shear over the Bay of Bengal.

• In 1999, N H Saji of Japan’s University of Aizu and others discovered an El-Nino Southern Oscillation (ENSO) -like phenomenon in the Indian Ocean, which they named the Indian Ocean Dipole (IOD).
• The Indian Ocean Dipole (IOD) is defined as the difference in the sea surface temperatures between two poles, i.e. Western pole in the Arabian Sea (western Indian Ocean) and the Eastern pole near Indonesia in the eastern Indian Ocean.  

• The IOD affects the climate of Australia, India and other countries surrounding the Indian Ocean and is a significant factor in deciding the rainfall variability in this region.

Case 1: Positive IOD

• In this, waters in the Western Indian Ocean (Arabian Sea) become relatively warm compared to waters in the Eastern Indian Ocean (south of Indonesia). 
• Studies have shown that a positive IOD year sees more than normal rainfall in central India. It happened in 1994 and 1997.  

Point to note: The Indian Ocean Dipole (IOD) and El Nino are independent climatic phenomena but often co-occur. When they co-occur (60% of the time), then two competing factors come into play at the same time i.e.

• El-Nino reduces high pressure at Mascarene high, which negatively impacts the Indian Monsoon.
• But at the same time, positive IOD favours good rainfall over Indian Subcontinent. 

This is the reason why we can’t say with certainty that El-Nino will result in lower rainfall over Indian Subcontinent. In 1997, there was intense El-Nino but above-average rainfall in India; in 2002, there was moderate El-Nino but intense drought in India. The reason for this was in 1997, there was a positive IOD which overpowered El-Nino, but in 2002 there was a Negative IOD which exacerbated the impacts of El-Nino.

Case 2: Negative IOD

• In this, waters in the Eastern Indian Ocean (south of Indonesia) become relatively warm compared to waters in the Western Indian Ocean (Arabian Sea). 
• In this case, more rainfall will happen in southern Indonesia and the eastern Indian Ocean.

Note: Worst drought occurs when El-Nino and Negative or Neutral IOD co-occur.

• India has an extraordinary variety of climates ranging from Tropical to Alpine.  
• The climate of India can be broadly described as Tropical Monsoon Type.

It is most affected by two seasonal winds.

The whole of India can be broadly divided into two climatic zones.

1. Longitudinal Extend

Since the Tropic of Cancer passes through the middle of India. Hence, 

• Northern India lies in the subtropical & temperate zone
• Southern India falls in the tropical zone. 

2. Distance from Sea

• Places situated near the sea have Equable Climates. A large area of India, especially the Peninsular region, is not very far from the sea. This part of the country does not have a very clearly marked winter, and the temperature is almost equal throughout the year. Kerala, situated on the coast, has an annual range of temperatures less than 3° C. 
• On the other hand, places situated away from the sea have Continental climates. In areas of central and north India, summers are hot, and winters are cold. 

3. Altitude

• Every 1000 metres of elevation gain results in a 6.5°C drop in temperature. Hence, places situated at higher altitudes are cooler than places on the plains.

4. Mountain Ranges

4.1 Himalayan Mountains

1. The Himalayas acts as a barrier to the freezing cold wind blowing from central Asia and keep the Indian subcontinent warm compared to Central Asia.
2. The Himalayas compel the South-West monsoon to shed whole rainfall in India.

4.2 Western Ghats

• Significant rainfall happens on the western slopes of the Western Ghats. In contrast, the eastern slopes & Deccan plateau receive very little rain as they lie in the rainshadow region of Western Ghats.

5. Direction of Surface Winds

• Summer: winds blow from sea to land, bringing widespread rain.
• Winter: winds blow from land to sea, and hence, they are dry & cold.

6. Upper-Air Circulation

They affect Indian Climate in the following ways 

• The onset of the South-West Monsoon is driven by the shift of the Sub-Tropical Westerly Jet (STWJ) from the plains of India towards the Tibetan plateau (explained in the next article in detail). 
• Sub-Tropical Westerly Jet (STWJ) reaches India after passing over the Mediterranean Sea, where rainfall occurs during winters. These winds bring cyclonic disturbances to Northern India, causing rain in Northern India during winters known as Western Disturbances. 
• The Tropical Easterly jet streams that blow over Peninsular India (approx. 14° N during summer) cause tropical depressions during the South-West and retreating monsoon.

• Rare Earth Metals include 15 lanthanides with Atomic numbers 57 to 71 and two non-lanthanide metals, i.e. Scandium and Yttrium.

• As they frequently occur in the same ore deposits as the lanthanides and have comparable chemical characteristics, scandium and yttrium are also regarded as rare-earth elements. But they have different electronic and magnetic properties.

• Although they are termed Rare Earth elements, they are not so rare in occurrence. However, 
  • They tend to occur together and are difficult to separate from one another. 
  • Along with that, they do not occur in concentrated form and are dispersed throughout the world. It makes their extraction difficult and economically unviable. 
  • They are also hazardous to extract due to their radioactive nature.  
• Two main ores from which Rare Earth Metals can be extracted are Monazite and Bastansite.

• There are two main sources
  • Bastnasite deposits in China and the United States constitute the largest percentage  
  • Monazite deposits found in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka and Thailand.  
• China is the world leader, accounting for around 97% of world production. India, Brazil, Australia, the USA, Russia, Thailand and Malaysia comprise the rest. 
• In 2023, large deposits of rare earth metals were found in Sweden. Until then, no rare earth deposits have been reported from the continent.
• Rare earth metals are also being recycled from e-waste. 

• India has 3% of world reserves. 
• The main source in India is monazite which is found in the form of sand on the beaches of Kerala. 
• The Geological Survey of India recently found a high concentration of rare earth elements in western Rajasthan.  

• Soil is the uppermost layer of the earth’s crust which can support plant life, and is usually composed of minerals, organic matter, living organisms, air and water.
• Naturally occurring soil is influenced by the following factors

• Soil formation begins with volcanic sedimentary or metamorphic rock material and can be seen in operation at an early stage on a recently formed volcanic island. 
• Rock is colonized by plants, suited to bare rocks like lichens and mosses, happens. 
• It is followed by the decay of plant material and the development of a thin organic layer on the rock.
• Wind, rain, snow and freezing cause erosion and rock fracturing, leading to more colonization and physical breakdown of the rock materials.
• After thousands of years, the upper layer of rocks will be converted into soils of many types.

Soil development begins with the colonization of parent rock by plants and animals. Due to various factors of erosion and transportation, different layers with different physical and chemical properties are formed. These are known as soil profile or horizons.

O-Horizon

• O-horizon is very common to surfaces with lots of vegetative cover. It is the layer made up of organic materials such as dead leaves and surface organisms, twigs and fallen trees.

A-Horizon

• A-Horizon is called Top Soil.
• It is rich in minerals as well as humus.
• Humus is generated by the decay of organic matter in the O horizon is carried downward by percolating water to enrich the A horizon.
• A horizon is dark because of a concentration of decomposed organic matter.

E-Horizon

• E-Horizon is usually lighter in colour
• This layer is rich in nutrients which are leached downwards from A and O horizons.

B-Horizon

• It is called Subsoil.
• It lies below the E-horizon 
• Most of the nutrients taken from the A and E horizons are deposited in this zone of accumulation.
• B horizon generally has little humus.

C-Horizon

• C-Horizon is the weathered parent rock.
• This layer is the first step in the development of soil and eventually gives rise to the top two layers. 

R-Horizon

• It is the unweathered parent rock.

Laterization

• Laterization is a soil-forming regime that occurs in humid tropical areas with high temperatures and abundant precipitation.
• The soil in this type of climate does not have an O-horizon (because of the rapid decomposition of organic material by microorganisms), and most of the minerals and silica of A horizon are leached downwards except for iron and aluminium compounds, which are insoluble primarily because of the absence of organic acids. 
• B horizon of Laterite soils is enriched in all the leached materials like silica.
• Lateritic soils are generally reddish in colour due to the presence of iron oxides

Podzolization

• Podzolization occurs mainly in the high middle latitudes where the climate is moist and cool.
• The soil in this type of climate has a thick O-horizon because, due to low temperatures, microorganism activity is reduced enough that humus accumulates. When water percolates downwards through the O-Horizon, it becomes acidic due to the formation of an Organic Acidic solution.
• Leaching by organic acidic solutions removes the soluble bases and aluminium and iron compounds from the A horizon leaving behind silica. The remaining silica gives a distinctive ash-grey colour.

Calcification

• In contrast to laterization and podzolization, which require humid climates, this occurs in arid regions with high temperatures where evaporation significantly exceeds precipitation.
• In arid regions, B horizon has high levels of Calcium. When water is evaporated from the upper layers of soil in these regions, water from the lower layers of soil mixed with Calcium comes up by capillary action. Hence, the proportion of calcium salts increases and soil salinity increases. 

1. Colour

• Soil colour might not be the most important attribute of soil, but it is certainly the most visible.
• A soil’s colour offers a clue to its physical and chemical characteristics
• E.g.: 
  1. Humus is black or brown, and soils with a high humus content tend to be dark. As soil’s humus content decreases because of either low organic activity or its loss by high microbiological activities, soil colours gradually fade to light brown or grey.
  2. Reddish soil usually indicates that iron is present in the soil.
  3. In cold-moist climates, a light grey soil indicates that iron has been leached out, leaving oxides of silicon  

2. Texture

oil texture refers to the size of grains that make up soil. Soil grains can be of the following types

Soil texture helps determine a soil’s capacity to retain the moisture and air necessary for plant growth. 

1. Soils with a higher proportion of larger grains (i.e. sandy soils) have many small passages between touching mineral grains, which allow water to seep downwards. They are well aerated as the space between the grains is occupied by air. But they allow water to seep through so quickly that plants cannot use it. 
2. Clay soils present the opposite problem. They have fine particles, resulting in smaller passages and spaces, so water penetrates slowly, and soils become waterlogged. But at the same time, they are deficient in air

Soils can be classified based on their proportion of sand, silt, and clay. Loam soils occupy the central areas of the triangular diagram. Loam is soil that contains a proportion of each of the three grades and, as a result, is most effective at storing moisture and air. This mixture is often added to gardens because it is particularly suitable for plant growth. Depending on which grade is dominant, loams can be further classified as sandy, silty, or clay-rich.

3. Soil Structure

• oil structure refers to the way soil grains are clumped together into larger masses called peds.
• Along with soil texture, soil structure also determines the permeability of water. Soils with the same texture but different structures can have different water permeability. 
• Soil structure can be of the following type

4. Soil Acidity and Alkalinity

• Soil pH is an important indicator of soil fertility as soil acidity, or alkalinity helps determine nutrient availability for plant growth.

Why is soil acidity important for the fertility of soil?

• Since plants receive virtually all their nutrients in solution, they can only absorb nutrients dissolved in liquid. However, if the soil moisture lacks some degree of acidity or is basicity, soil water has little ability to dissolve these nutrients. As a result, even though nutrients are in the soil, plants may not have access to them. 
• To correct alkalinity, which is common in the soils of arid regions, farmers can flush the soil with irrigation water. 
• Strongly acidic soils are also detrimental to plant growth. In acidic soils, soil moisture dissolves nutrients, but they may be leached away before plant roots can absorb them. Soil acidity can be corrected by adding lime to the soil.

• Plantation crops are grown for the purpose of export. In India, they are generally grown in large estates on sloping hills.
• The main plantation crops grown in India are tea, coffee, rubber, and spices. 

• Tea is an evergreen plant that mainly grows in tropical and subtropical climates.
• Tea is made from dried leaves of the tea plant. When added to boiling water, the theine in it serves as a stimulant.
• There are at least 6 different types of Tea 
  1. White Tea: Wilted and unoxidized
  2. Yellow Tea: Unwilted and unoxidized
  3. Green Tea: Unwilted and unoxidized
  4. Oolong Tea: Wilted, bruised and partially oxidized
  5. Black Tea: Wilted /sometimes crushed
  6. Post-fermented: Allowed to ferment / compost.

History

• Although Tea is said to be indigenous to China, Major Robert Bruce noted in 1823 that tea bushes grew freely on the slopes of upper Assam’s hills.
• In 1840, tea seeds were smuggled out of China, and commercial tea plantations were set up in the Brahmaputra valley. 

Conditions required for growing Tea 

Producer States

In India, it is mainly grown in 

• North East India (Assam (51%) and Darjeeling hills of West Bengal (22%))
• South India (Nilgiri hills, Cardamom, Palani and Anaimalai Hills) 
• North-West India (Kangra Valley and Mandi of Himachal Pradesh and Dehradun, Almora and Garhwal district of Uttarakhand)

Note: Green Tea is produced in the Kangra Valley of Himachal Pradesh.

Side Topic: Darjeeling Tea

• Darjeeling Tea of India is famous worldwide for its unique aroma and taste.
• It has the GI Tag (in fact, it was the first product from India which was granted the GI Tag).

• Rubber is a coherent elastic solid obtained from latex. 
• A rubber tree is a quick-growing tall tree acquiring 20-30 m height in 5 to 7 years after planting.
• Rubber is used for various purposes like tyres, tubes, erasers and industrial products.
• The first rubber plantations in India were set up in 1895 on the hill slopes of Kerala. 

Conditions required for growing Rubber 

Producer States

In India, it is produced in Kerala (92%), Tamil Nadu (3%), Kerala (2%) and Andaman and Nicobar (~2%).

• India has been world-famous for its spices since ancient times. 
• These spices are mostly used for flavouring cooked food and for preparing medicines, dyes etc. 
• Pepper, chillies, turmeric, ginger, cardamom, clove and areca nut are the major spices cultivated in India. 
• Kerala is the leading producer of spices in India.  

• The crops which are cultivated for commercial purposes are called cash crops.
• These crops include sugarcane, tobacco, fibre crops (cotton and jute), tea, coffee and oilseeds.

• Sugarcane is India’s most important cash crop, and India is the second largest producer of sugarcane globally.
• This crop provides the raw material for the sugar industry.
• Besides providing sugar, gur and khandsari, it supplies molasses for the alcohol industry and bagasse for the paper industry.

Conditions required for growing Sugarcane 

Producer States

At the state level, Uttar Pradesh is the leading producer of sugarcane, followed by Maharashtra, Karnataka, Tamil Nadu, Gujarat, Punjab, Haryana and parts of MP and Bihar.

Traditionally sugarcane areas were northern plains, especially UP. But its cultivation has gradually shifted towards the south.  The reason for this is the fact that North Indian sugarcane is :

• Subtropical variety 
• Low sugar content 
• Sugar factories are shut in winter as sugarcane is grown only in summer.  

Hence, when irrigation developed in the southern states, the sugarcane industry developed there as well.

• Cotton is the most important cash crop in India. 
• It provides raw materials to India’s most significant industry, i.e. Textile Industry. 
• Besides the cotton fibre, its seed acts as raw material in the Vanaspati industry. Additionally, cotton seed can be used as fodder for milch cattle.
• India ranks second next to China in the production of cotton.

Conditions required for growing Cotton 

Cotton is a tropical and subtropical crop requiring uniformly high temperatures. Conditions for its growth are 

Varieties of Cotton

There are three main varieties of cotton grown in India. 

1. Long Staple Cotton

• It has the longest fibre, with lengths varying from 24 to 27 mm.
• The fibre is long, fine and shining and is used for making fine and superior-quality cloth.
• 50% of the total cotton produced in India is of this variety.
• It is grown in Punjab, Haryana, Maharashtra, Tamil Nadu, MP, Gujarat and Andhra Pradesh.

2. Medium Staple Cotton

• The length of its fibre is between 20 to 24 mm.
• 44% of the total cotton produced in India is of this variety.
• It is grown in Punjab, Tamil Nadu, Madhya Pradesh, UP, Karnataka and Maharashtra.

3. Short Staple Cotton

• It is an inferior variety whose length is less than 20 mm. 
• About 6% of the cotton grown in India is of this type.

Producer States

Leading producer states include Gujarat (35%), Maharashtra (21%), Andhra (14%), Haryana (8%), Punjab (7%), MP (6%), Rajasthan (4%) and Karnataka (3%).

• Jute, also known as ‘Golden Fibre’, is an important cash crop.
• It provides the raw material for the Jute industry. It is used to manufacture gunny bags, carpets, hessian, ropes and strings, rugs, clothes, tarpaulins, upholstery etc. 
• It has high tensile strength and low extensibility and ensures better breathability of fabrics.
• It is 100% bio-degradable and recyclable and thus environmentally friendly. 

Conditions required for growing Jute 

It is a tropical fibre crop and requires the following conditions

Producer States

• India suffered a great setback during the partition of India in 1947 because 75% of the jute growing areas went to Bangladesh while the jute mills remained in India. The government has made great efforts to increase the production and area under jute in India.
• The main producer states in India include West Bengal (80% production), Bihar, Assam and Odisha.

• Tobacco was brought to India by the Portuguese in 1508. since then, its cultivation has spread to different parts of the country. At present, India is the major producer of tobacco in the world.
• Apart from oral consumption, tobacco is mainly used for cigarettes, bidi, cigars and hookah. It is also used in the production of insecticides. 
• There are two varieties of tobacco. These include 
  1. Nicotiana Tabacum: High-quality tobacco used in cigarettes, cigar bidi, chewing, hookah and pipe. 90% of tobacco grown in India is of this variety. 
  2. Nicotiana Rustica: Inferior and short quality used in hookah, chewing and snuff. 10% of tobacco grown in India is of this variety.

Conditions required for growing Tobacco 

Conditions for the growth of tobacco includes

Producer States

It is grown in 15 states of India. But 66% of production comes from Gujarat and Andhra Pradesh. 

• Due to its large population and limited land, Indian agriculture is largely dominated by food crops.
• Food crops include cereals and pulses, amongst which rice, wheat, jowar, bajra, maize, barley, ragi, gram and tur are important.

• Rice is an indigenous crop and staple food of the majority of Indians.
• After China, India is the second-largest rice producer in the world.

Conditions required for growing Rice

Producer States 

• West Bengal (largest producer in India), UP, Punjab, Tamil Nadu, Bihar, Andhra, Odisha, Assam, & Haryana.

Issues associated with its cultivation

• Due to the increased use of High Yielding Variety (HYV) seeds (CR Dhan 205, AR Dhan 306, CRR 451 etc.), many indigenous varieties have disappeared.
• It is a water-guzzling crop grown in arid regions like Punjab and Haryana with the help of tubewell irrigation. It has led to a rapid downfall in the groundwater level.

• Wheat is the country’s second most important food crop, after rice.
• India ranks 5th in the production of wheat in the world. 

Conditions required for growing Wheat 

Producer States

• Over 85% of India’s wheat production comes from 5 states, namely Uttar Pradesh (highest producer), Punjab (highest yield per hectare), Haryana, Rajasthan and Madhya Pradesh. 
• Apart from these regions, the black soil tract of the Deccan covering parts of Maharashtra and Gujarat also grows wheat.

• India is world’s top producer & consumer of pulses. But even after that, India is not self-sufficient in the case of Pulses.

• Major pulses that are grown in India: are tur, urad, moong, masur, peas and gram.
• Pulses can be grown in all parts of the country except the heavy rainfall areas. 

The share of different pulses in total pulse production 

The area under pulses has decreased in the country. The main reason is the area under pulses is being shifted to the more profitable crops like rice and wheat after the green revolution.

Importance of Pulses

• Pulses are rich in vegetable protein. Since most Indians are vegetarians. Hence, pulses are the primary source of protein for a majority of people
• Pulses are leguminous crops which can fix atmospheric nitrogen in the soil and hence are usually rotated with other crops.

Government Initiatives to promote Pulse Production

1. National Food Security Mission (NFSM)-Pulses: Aims to Increase Pulses production by 3 Million tonnes 
2. Increase in MSP of Pulses 
3. Price Support Scheme (PSS) under PM-AASHA 
4. Creation of Buffer Stock of Pulses by NAFED. 
5. Price Stabilization Fund Scheme to check volatility in the prices.