Pressure belts of the World Upsc

Pressure belts of the World

There is a relationship between temperature and the atmospheric pressure of place. This is not uniform everywhere in the world. As some places on the earth have low pressure and some places on the earth have high pressure. This is greatly modified by the rotation of the earth.

These permanent pressure belts are unstable as they shift northward during summer and southwards during winter. This is caused by the movement of the sun between the Tropic of Cancer and the Tropic of Capricorn.

There are four major Permanent pressure belts of the World

  1. Equatorial Low-Pressure Belt (5° N to 5° S)
  2. Sub-Tropical High-Pressure Belt ( (30° N & S to 35° N & S)
  3. Sub-Polar Low-Pressure Belt ( (60° N & S to 65° N & S)
  4. Polar High-Pressure Belt ( (90° N & S)
Permanent pressure belts of the World
Permanent pressure belts of the World

Low-Pressure Belt

Doldrum

The Doldrum is also called equatorial low. It lies along the Equator and at a range of 5° north and south. This is an equatorial low-pressure belt. Here the temperature is high throughout the years.

Due to the high temperature, the air rises and expands, which causes this low-pressure belt.

Sub-Polar Low-Pressure Belt

This lies in the range of 60° and 65° north and south latitudes. The low pressure is caused due to the rotation of the earth. These are caused by the air that moves from high-pressure polar areas also from the air that comes from the subtropical high-pressure areas.

These two air meets at 60° North and 60° South latitudes. This makes the air rise and causes a low-pressure belt in these regions.

High-Pressure Belt

Sub tropical High Pressure Belt

These lie in the latitude of 30-35° North and 30-35° South of the Equator. This over here raises up due to heating moves towards the Poles. But this warm air cools down and sinks at 30° North and 30° South latitudes. Here it piles up to create high-pressure belts.

This sub-tropical high pressure is also called Horse Latitudes.

Polar High-Pressure Belt

Polar High-Pressure belts lie near the poles. This region is extremely cold. This makes the air cold, dense, and Heavy. The accumulation of heavy air in this region causes High-Pressure Belt.

This location is not fixed and moves towards the south and north as per the position of the Sun.

FAQ

1.Equatorial low-pressure belt is called?

It is called Doldrum. It is because it is a zone of total calm without any breeze. Here the air circulated in an upward direction and there is only little surface wind in ITCZ. The sailors know this are is calm for sailing ships for weeks.

Horticulture Crops in India Upsc

Fruits, vegetables, and flowers are horticulture crops. India is the second-largest producer of Horticulture crops. Apple is mostly produced in Himachal Pradesh, Jammu and Kashmir, and Uttarakhand.

Banana cultivation is mainly in Tamil Nadu and Maharashtra. Orange cultivation is mainly in Maharashtra, Uttarakhand, Himachal Pradesh, Jammu and Kashmir, Tamil Nadu, and Karnataka.

Grape cultivation is mainly in Uttarakhand, Himachal Pradesh, Jammu and Kashmir, Maharashtra, Andhra Pradesh, Tamil Nadu, and Karnataka. India produces 13% of the world’s production of vegetables.

State wise horticulture production in India

Andhra Pradesh

The Major fruit crop grown in Andhra Pradesh is Banana, Sweet Orange, Mango, Guava, and Pomegranate. The vegetable crops are Tomato, Beans, Brinjal, Bhendi, Onion, Chillies, etc.

Andra Pradesh emerges as are second-largest fruit-producing state in India and accounts for 11.8% of total fruits produced in the country. Banganapalle Mangoes are famous in Andra Pradesh, and this state got GI Tag for Banganappale Mangoes.

Arunachal Pradesh

The major fruits grown in Arunachal Pradesh are Litchi, Banana, Jack fruit, Orange, Pineapple, etc. The major vegetable grown in Arunachal Pradesh is Potatoes, brinjal, ginger, chilies, pumpkin, cucumber, cowpea, etc.

Also, nuts like Peach Walnut, almond, etc are also grown in this state.

Assam

Major fruit crops grown in the state are Banana, Pineapple, papaya, Assam lemon, Orange, Guava, Litchi, Jack fruit, and Mango. The vegetables are Potato, Sweet Potato, Tapioca, Onion, etc.

Bihar

Mango, guava, litchi, and banana are the major fruit crops of Bihar. The major vegetable cultivated in Bihar is potato, onion, eggplant, and cauliflower.

Chhattisgarh

The Major vegetable grown here is Cauliflower, cabbage, brinjal, tomatoes, ladyfinger, potatoes, green peas, karela, loki, torai, munga, kochai (arwi) carrot, parwal, onion etc. The major fruits grown in Chhattisgarh are Guava, Mango, Lime, Cashewnut, Cheku, Litchi, etc.

Goa

The major vegetable grown in Goa is Brinjal, Bhendi , Chillies, Cucumber, Pumpkin, Gourds, Musk Melons, Red amaranthus, Raddish, Knol-Khol, Cabbage, Bottle gourd, Long beans, Cluster beans, etc. The major fruits grown in goa are apples, pears, strawberries, grapes, melons, and watermelons.

Gujarat

The major vegetables grown in Gujarat are Onion, Garlic, Potato, Brinjal, Tomato, Okra, and Cucurbits. The major fruit crops grown in Gujarat are Banana, Mango, Citrus, Papaya, and Sapota.

Haryana

The major vegetable grown in Haryana is pea, tomato, potato, carrots, garlic, onion, etc. Also, the major fruits grown in Haryana are mango, litchi, chickoo, citrus fruits like oranges and ber.

Himachal Pradesh

The major vegetable grown in Himachal Pradesh is tomato, cauliflower, cabbage, pea, and capsicum. The major fruits varieties grown in Himachal Pradesh are Mango, Litchi, Guava, Loquat, Citrus Fig, Ber, Papaya, Grapes, Jack Fruit, Banana, Low chilling varieties of Peach, Plum and Pear, Strawberry.

Jharkhand

The major fruit grown in Jharkhand is Mango, Guava, Litchi, Lemon, Banana, Papaya, and Jackfruit. The major vegetable grown in Jharkhand is potato, tomato, ladyfinger, peas, cauliflower, brinjal, & cabbage.

Karnataka

The major fruits grown in Karnataka are Mango, Chikku, Guava, Custard, Soursop, Bur, Pomegranate, Fig, Jack fruit, etc. The major vegetables grown in Karnataka are tomatoes, Beans, Peas, etc.

Kerala

The major fruits grown in Kerala are Mango, Grapes, Banana, Jackfruits, Star gooseberry, Indian hog plum, Custard Apple, Papaya, etc. The main vegetables grown in Kerala are Okra, Tomato, Chilli, Bitter Gourd, Radish, Cucumber, Pumpkin, Brinjal, etc.

Madya Pradesh

The major fruits grown in Madhya Pradesh are Guava, Mango, Banana, and Orange. The major vegetable grown in Madhya Pradesh is Green Peas, Potatoes, Onion, Tomato, etc.

Maharashtra

The major fruit crops cultivated in Maharashtra are Mango, Cashew, Pomegranate, Citrus, Sapota, Banana, Grapes, and Guava. The major vegetables cultivated in Maharashtra are Beetroot, Bitter Gourd, Bottle Gourd, Cabbage, Cauliflower, Green left Caladium, Potato, Carrot, Onion, Yam(Kangar), Radish, etc.

Manipur

Banana, Pineapple, and Citrus have a major share in area and production, and also the Guava, Papaya, etc are grown on a large scale. Banana is native to this region and is called Tamenglong. Pineapple is grown on the hilly slopes.

Vegetables grown in Manipur are Cucurbits, Tomatoes, Brinjal, Bhindi, Cabbage, Cauliflower, Potato, Radish, Carrot, Broccoli, Capsicum, etc.

Meghalaya

In Meghalaya state, sub-tropical fruits are grown that include citrus species, pineapple, banana, guava, jack fruit, and papaya, and also temperate fruits such as pear, peach plums are grown in the Khasi Hills districts. The famous fruit in Meghalaya is Sohphie which is common.

Important vegetables grown in Meghalaya are cucumber, bitter gourd, brinjal, pumpkins, a number of green leafy vegetables, etc.

Mizoram

The major fruits grown in Mizoram are Mandarin Orange, Mango, Grape, Pineapple, Banana, and Strawberry. And also recent addition is Dragon fruit.

The major vegetables grown in Mizoram are Chayote, pumpkin, ash gourd, Cucumber, Bitter melon, etc.

Nagaland

There is a lot of native fruits in Nagaland such as persimmon, walnut, hazelnut, peach, lemon, avocado, Naga Apple, etc. The major vegetables cultivated in Mizoram are cabbage, cauliflower, knol-khol, radish, carrot, French bean, etc.

Odisha

The major fruits grown in Odisha are Mango, Banana, cashew, Jackfruit, Lemon, and Sapota. The major vegetables grown in Odisha are Tomato, Capsicum, Cabbage, Cauliflower, Carrot, Beat, Pea, Brinjal, Bhendi, Cucumber, etc.

Punjab

The major fruits cultivated in Punjab are Sweet Orange, lime, lemon, litchi, guava, pear, peach, grapes, ber, banana, etc. Also, the main vegetables cultivated in Punjab are Potato, Onion, Garlic, Tomato, etc.

Rajasthan

The major fruits cultivated in Rajasthan are Aonla, Banana, Ber, Blackberry, Custard Apple, Date Palm, Grapes, Guava, Lemon, Mango, Papaya, Sapota, etc. The major vegetables cultivated in Rajasthan are Brinjal, Cucurbits, Okra, Onion, Potato, Tomato, etc.

Sikkim

The major fruits cultivated in Sikkim are Banana, Papaya, Guava, etc. The major vegetables cultivated in Sikkim are Tomato, Broccoli, Iskus or Chayote, Cauliflower, etc.

Tamil Nadu

Mango and Banana are the most cultivated crops in Tamil Nadu that account for over 81% of the total fruit production. The other major fruits grown in Tamil Nadu are Lemon, Guava, Water Melon, Amla, Jackfruit, Grapes, Papaya, etc.

The major cultivated in Tamil is Tapioca, Onion, Brinjal, Tomato, and Ladies finger. These accounts for over 70% of the total area and as well as production. The other major vegetables grown in Tamil Nadu are Capsicum, Carrots, potatoes, green peas, green chilies, etc.

Telangana

The major fruits grown in Telangana are Mango, banana, guava, papaya, and citrus. The other major fruits grown in Telangana are Muskmelon, Watermelon, Sapota, Sweet Orange, etc. The Major vegetables grown in Telangana are Tomato, Brinjal, Bhendi, and different types of gourds.

Tripura

The major fruits grown in Tripura are Jackfruit and Pineapple. Other fruits are Mango, Orange, Banana, and Litchi. The major fruits cultivated in Bean, Cabbage, carrot, etc.

Uttarakhand

The major vegetables grown in Uttarakhand are Potato, Tomato, Cauliflower, Capsicum, etc. The major fruits grown in Uttarakhand are Litchi, guava, apricot, Strawberry, Plum, Indian Hawthorn, etc.

Uttar Pradesh

The major fruits grown in Uttar Pradesh is Mango, guava, aonla, banana, jack fruit, ber, citrus, etc. And the major vegetables are grown in Uttar Pradesh are Potato, Brinjal, Cauliflower, Cabbage, Spinach, Melon, Carrot, etc.

West Bengal

The major fruits grown in West Bengal are Mango, Pineapple, Banana, Citrus, Litchi, Guava, Papaya, etc. Also, the Major vegetables grown in West Bengal are Brinjal, Cabbage, Cauliflower, Cucumber, Radish, etc.

Union Territories

Andaman and Nicobar Islands

Andaman and Nicobar Islands are hilly lands. Here major fruits grown are Mango, Pineapple, Guava, Jackfruit, Citrus, Sapota, etc. The Major vegetables grown in this Island state are Bhindi, Lobia, Brinjal, Marsa, Poi, Radish, Cucurbits, etc.

Chandigarh

The major fruits produced in Chandigarh are Mangoes, Guava, Lemons, Phalsa, Chikoo, Amla, Peach, etc. The Major vegetables grown in Chandigarh are Tomato, Onion, Garlic,

//Draft

Livestock farming in India Upsc

One source of income for the farmer helps a lot during crop failure. It contributes 4% of GDP.

India contributes 11.6 % of livestock in the world, which is number one.

Distribution of livestock in India
Livestock in Indian states

i.Cattle

Cattle constitute 37.3 percent of the livestock population in India. India has second-largest cattle population after Brazil.

Madhya Pradesh tops with 10.3 % followed by Uttar Pradesh (10.2 %) and West Bengal (8.7 %). Cattle population includes 1) Milch Breed, 2) Draught breed and 3) Mixed or General breed.

Livestock
population of India in 2012

ii.Goats

Called a poor men’s cow, it provides milk, meat, skin, and hair. By the number of goats, Rajasthan is first with 16% followed by Uttar Pradesh and Bihar.

iii. Buffaloes

A vital source of milk in-country and UP has 28% of countries buffaloes followed by Rajasthan (9.6%) and Andhra Pradesh(7.9%).

Livestock Census

The livestock census was first conducted in the title of Dairy Cattle Census. The 19th Livestock census was conducted in 2012 October, it is conducted every 5 years.

Department of Animal Husbandry at the state level and Regional Joint Director at District level under the guidelines of Government of India Ministry of Agriculture and farmers welfare, Department of Animal Husbandry Dairying and Fisheries conducts the census.

Started in 1919 – 1920, conducted every 5 years.

As of now, a total of 19 Livestock census has been conducted.

Dairy, Meat and Wool Production

As per Animal Husbandry Department, during 2016-17, the total milk production is 163.7 million tons.

a.Dairy

Uttar Pradesh with 27.6 million tonnes (16.8%) was leading, followed by Rajasthan with 19.4 million tonnes (11.8 %) and Madhya Pradesh with 13.4 million tonnes (8.2 %).

b. Meat

The total meat production of the country is 7.4 million tonnes.

UP is leading with 1.3 million tonnes (18.2%), Maharashtra (11.4%), and West Bengal(18.2%) produces 0.8 million tonnes.

c. Wool

43.5 million KG of wool produced as per 2016-17 report. Rajasthan leads 14.3 million KG (32.9%) followed by Jammu and Kashmir(16.7) with 7.3 Million Kilogram and Karnataka(15.1%) with 6.6 Million Kilograms.

Fisheries

One of the important economic activities in the country. It employs over 14 Million People. India produces 3% of the world’s fish, standing second after China.

It gives good foreign exchange, employment to the nation. India has a coastline of 7517 Km and the mainland’s length is 6100 km. In India fishing is of two types:

Marine or Sea Fisheries:

India has a continental shelf up to the depth of 200 m. It includes coastal, off-shore, and deep-sea fishing. Kerala’s top fish production in India.

Inland or Fresh Water Fisheries:

Fishing in freshwaters such as lakes, canals, ponds, tanks, etc. About 50% of the country’s fish comes from inland fishing.

Andhra is the leading inland fish producer in India. Important fish varieties of India are Herrings, Mackerel, Cat Fish, Perches, Eels, Mullets, etc.

Total Inland fish production 65.77 Lakh tons in 2014-15. In India, the top five fish-producing states are Andhra Pradesh, West Bengal, Gujarat, Kerala, and Tamil Nadu.

Agriculture revolutions in India
Agriculture revolutions in India

Commercial crops in India and its growing areas Upsc

Commercial crops in India

Commercial crops are crops that are planted mainly for the purpose of selling on the market to make exports and to make high profits. They are also called cash crop or profit crop that is grown to sell for profit. These crops are usually purchased by third parties such as agents, brokers, factories, corporates etc.

Also, these crops are readily salable crops produced or gathered mainly for the international market.

At the international level commercial crops are cocoa, oil palm, rubber, kola etc.

Commercial crops in India are crops such as fibre ( cotton, mesta, and jute), Sugar (Sugarcane), and Oilseeds (Linseed, Sunflower).

i. Sugarcane

Sugarcane is the most important cash crop in the country and India is the second-largest producer(Kindly check the latest).

It is the raw material for the sugar industry and also provides gur and khandsari, molasses for alcohol industries. For Paper producing industries it provides Bagasse.

Maharashtra, Karnataka, Tamil Nadu, and Gujarat are the largest producer of Sugar in India. Sugarcane takes almost a year to grow.

cash crops in india map - commercial crops in india upsc
Major Cash Crops in India Map as per States

ii. Cotton

It provides raw materials for Textile Industries and India is the second-largest producer of Cotton after China.

Cotton Producing States are Gujarat, Maharashtra, Andhra Pradesh, and Punjab which account for 79% of the country’s production.

iii. Jute

The tropical crop grows in alluvial soil.

Provides raw materials for Gunny bags, ropes, strings, carpet, hessian, rugs, clothes, tarpaulin, and upholstery.

In the production and cultivation of jute, West Bengal stands first, other cultivators are Bihar, Meghalaya, and Assam.


iv. Oil Seeds

Crops such as Linseed, Castor, Niger seed, Groundnut, etc are oilseed crops. These provide oil and oil cakes used to make lubricant, candles, cooking oil, etc.

Gujarat is the largest oil producer followed by Rajasthan, Madhya Pradesh, Maharashtra, and Andhra Pradesh.

India is the second-largest groundnut producer after China.

3.Plantation crops

Cultivated in hilly areas, used mostly for exports. Tea, coffee, rubber, and spices are the major plantation crops of India.

i. Tea

It grows in tropical and subtropical regions, it is also an evergreen plant. Tea is a labor-intensive crop and light shade is required for its rapid growth.

It requires high rainfall, but its roots cannot withstand waterlogging. These two varieties of Tea are cultivated in India namely Bohea from China and Assamica.

Also, some hybrid varieties are cultivated. India is the second-largest producer after China.

Assam is the largest producer, Tamil Nadu, Kerala, and West Bengal are other producers.

ii. Coffee

coffee growing areas in india map
coffee-growing areas in India map By Nicahlp, modified by Dr. Blofeld – Self-made based on File: India-locator-map-blank.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12186054

Grow in shady regions above 1000 and 1500 meters above sea level. There are two main varieties of Coffee Cultivated in India one is High quality ” Arabica ” which is cultivated more and the other is Robusta which is of Inferior quality.

India is the seventh-largest producer of Coffee. Karnataka is the largest producer of Coffee in India. It produces 71% in India and 2.5% in the world.

iii. Rubber

This plantation was first established in Kerala in 1902, these crops grow where the temperature is above 20 degrees Celsius and rainfall above 300 cm.

Major rubber producers are Tamil Nadu, Karnataka, Andaman Nicobar Islands, and Kerala.

major rubber producing states in india map

major rubber producing states in india map

iv. Spices

  • Used for flavoring of foods and for medicines.
  • Pepper, areca nut, ginger, clove, cardamom, chilies are major spices.
  • In India Kerala is the largest producer of spices.

Types of farming in India and their main features Upsc

Types of Farming

There are primarily six types of farming, particularly practised in India. They are Subsistence farming, Shifting Agriculture, Intensive farming, Dry Farming, Mixed farming and Terrace farming.

a) Subsistence Farming

Poor farmers with small land holding grow crops with the help of family members with little or no modern inputs. In this type of farming the farmer use the entire agricultural farm, they get little surplus to sell in the market.

In addition, food crops such as cotton, jute, oilseeds, tobacco, and sugarcane are cultivated. As a result of using the traditional method, productivity is low. Parts of Rajasthan, UP, and Madhya Pradesh are the places where subsistence farming is practised.

Modern Facilities such as irrigation, electricity, machines etc are not available to this. The farming is done manually.

b) Shifting Agriculture

Shifting agriculture is performed in forest land by tribal people, mostly. Farmland is created after cutting and burning trees.

Crops are grown until the soil is fertile, for two, three years. Then the farmer move to a new piece of land after the soil loses its fertility also called “Slash and Burn Cultivation“.

This type of agriculture is called Jhum in Assam, Poonam in Kerala, Podu in Andhra Pradesh and Odisha, and Beewar, Mashan, Penda, Beera in Madhya Pradesh.

c) Intensive Farming

It is a method of agriculture where the latest technologies and intensification methods are used to maximize the yield.

Also used for livestock such cows, pigs, and chickens raised in the indoors. It is also known as Factory Farms.

Intensive farming is practised in Rajasthan, UP, Madhya Pradesh.

d) Dry Farming

Dry Farming is also called Dryland Farming. In this farming, the cultivation of crops is practised in areas where irrigation is lacking, Like arid areas, typically less than 50 centimetres of precipitation annually. Dryland farming is based on efficient storage and utilization of limited moisture in the soil.

Also, crops selection is important for Dry farming. Dry climate withstanding crops are grown with the help of irrigation also grown under dry farming. The tilling is done in the land shortly after the harvest to capture the moisture from the air.

The moisture is regulated in the primary by removal of weeds and by runoff prevention. The Dry farming crops are selected, to be drought resistant or drought evasive. Example: Sorghum. This is because such crops reduce transpiration or reduce the emission of moisture and stop their growth. And resumes its growth after the conditions are favourable.

Yield is low and only one crop per year. This is practised in Drier parts of Rajasthan, Gujarat, Madhya Pradesh, etc.

e) Mixed Farming Agriculture

It is a method of agriculture where crops, livestock, fisheries, beekeeping, etc. are done in the same place.

Cropping pattern in India - Mixed Farming Agriculture
Mixed Farming Picture

f) Terrace Cultivation

Terrace Cultivation is practised in hilly areas, where there are slops, and the availability of flat land is limited. Soil erosion is also checked by Terrace farming.

Used in Hilly areas. Terrace cultivation is practised in Punjab, Meghalaya, Haryana, Uttar Pradesh, Himachal Pradesh, and Uttarakhand.

Agriculture seasons in India
Cropping Seasons in India

Water resources Tnpsc Samacheer Notes

1. Introduction and Nature of Water

  • Water is one of the most important and indispensable elements on Earth without which life cannot exist.
  • All plants and animals require water for survival.
  • In addition to drinking, water is required for domestic, agricultural, and industrial purposes, and is essential for carrying out almost all economic activities.
  • Water resources are potentially useful to humans.
  • Water acts as a natural filter in the soil and purifies it.
  • Water is an abiotic and renewable natural resource that supports ecosystems.

2. Status and Global Distribution of Water

  • Coverage & Total Quantity:
    • About 71% of the Earth’s surface is covered by water.
    • Total water present on Earth is approximately 326 million cubic miles.
  • Salt Water vs. Fresh Water:
    • Salt water (oceans, seas) constitutes about 97.20% (or 97.2%) of total water.
    • Fresh water constitutes only about 2.80% (or 2.8%).
  • Breakdown of Fresh Water (2.80%):
    • Surface water: Accounts for 2.20% (or 2.2%) (also broken down as 0.30% of total fresh water in specific diagrams).
    • Groundwater: Accounts for 0.60% (or 0.6%) (or 30.10% of fresh water).
    • Others: Make up 0.90% (or 0.9%).
  • Breakdown of Surface Water:
    • Glaciers and icecaps: Represent 2.15% of surface water (or 68.70% of fresh water).
    • Lakes and streams: Comprise 0.01% (with lakes representing 87% and rivers 2% of liquid surface fresh water).
    • Swamps: Comprise 11% of surface fresh water.
    • Other forms: Account for 0.04%.
  • Extractable Groundwater:
    • Only about 0.60% of total groundwater can be economically extracted with present drilling technology (noted in older editions as 0.25% of the 0.6% groundwater).

3. Estimated Volume of Water by Source (Shiklomanov, 1993)

  • Oceans, Seas, & Bays: 321,000,000 cubic miles (96.54% of total water).
  • Ice caps, Glaciers, & Permanent Snow: 5,773,000 cubic miles (1.74% of total water).
  • Groundwater: 5,614,000 cubic miles (1.69% of total water).
  • Soil Moisture: 3,959 cubic miles (0.001% of total water).
  • Ground Ice & Permafrost: 71,970 cubic miles (0.022% of total water).
  • Lakes: 42,320 cubic miles (0.013% of total water).
  • Atmosphere: 3,095 cubic miles (0.001% of total water).
  • Swamp Water: 2,752 cubic miles (0.0008% of total water).
  • Rivers: 509 cubic miles (0.0002% of total water).
  • Biological Water: 269 cubic miles (0.0001% of total water).

4. Water Resources in India

  • Sources of Water: Water in India is available through three primary sources:
    1. Precipitation
    2. Surface water
    3. Groundwater
  • Perennial Rivers:
    • Porunai (Thamirabarani): The only perennial river in Tamil Nadu, flowing through Tirunelveli and Thoothukudi districts.
    • Archaeological excavations at Adichanallur and Sivakalai date the Thamirabarani civilization to circa 1155 BC (BCE), making it nearly 3,200 years old.
  • Other Historical River Systems:
    • Kosasthalaiyar River: Considered one of the major cradles of human ancestors in the world.
    • Ganga (Ganges) and Brahmaputra: Major river valleys that provided fertile alluvial lowlands, supporting dense populations, agriculture, and early urban centers.
    • Pennar River: Flowing through the Erramala hills in Kadapa district, Andhra Pradesh, it created the spectacular Gandikota Gorge (known as the Grand Canyon of India).
    • Narmada River: Forms a rift valley between the Vindhyas and Satpura ranges and develops an estuary in Gujarat.
    • Kaveri (Cauvery), Vaigai, Noyyal, and Tungabhadra: Served as historic centers of agriculture, deltaic irrigation, and town settlements.
  • Per Capita Urban Consumption:
    • Average daily per capita water consumption is 250 liters in Kolkata, 175 liters in Mumbai, and 80 liters in Delhi (compared to 1,200 liters in Los Angeles and 1,100 liters in Chicago).
  • Urban Scarcity & Regulation:
    • Acute water scarcity exists in Indian urban centers; cities such as Chennai, Hyderabad, Jaipur, Jodhpur, Nagpur, Shimla, Solan, Surat, Udaipur, and Vadodara permit only 1 to 2 hours of water supply per day.
    • New Delhi regulates water supply to approximately 4 hours per day.
  • Marine & River Pollution:
    • Most urban garbage and sewage in India are dumped into rivers or along their banks.
    • Major coastal cities including Mumbai, Kolkata, and Chennai continuously discharge substantial portions of untreated waste into the sea.

5. Water Management and Irrigation History in India

  • Prehistoric & Sangam Periods:
    • Irrigation management began during the Iron Age/Megalithic period, with settlements deliberately situated near rivers and tanks.
    • Ancient settlements utilized ring wells and brick-built tanks for water storage (excavated at Arikkamedu and Keezhadi).
    • At Adichanallur, advanced water and sewage management included raised brick structures with 29 courses of bricks and perforated terracotta pipes arranged in 9 courses.
    • King Karikalan Chola effectively utilized water from the River Kaveri, establishing extensive canal systems that peaked during the 10th to 13th centuries.
  • Medieval Systems:
    • Agriculture depended heavily on irrigation via rivers, canals, tanks, and wells.
    • In the 14th century, Firuz Shah Tughluq constructed India’s largest known network of canals in the Delhi area.
    • Water extraction utilized lift irrigation and the Persian wheel in North India.
    • Check dams, reservoirs with sluice gates, and Chola canal networks linked Kaveri’s tributaries.
    • Village assemblies (ur, nadu, brahmadeya, and nagaram) were tasked with maintaining local water bodies and irrigation infrastructure.
  • Ancient State Policy:
    • Under the Mauryan Empire, the central administration directly initiated and organized irrigation projects while regulating water distribution.

6. The Hydrological (Water) Cycle

  • Definition & Characteristics:
    • Hydrology is the science dealing with the occurrence, distribution, movement, and properties of water on Earth.
    • The cycle is a continuous, sun-driven process transporting water from oceans to the atmosphere, from atmosphere to land, and back to oceans.
    • It represents a closed system where the overall volume of water remains constant, though its spatial and temporal distribution varies.
  • Three Primary Phases:
    1. Evapotranspiration
    2. Precipitation
    3. Runoff
  • Six Core Components:
    1. Evapotranspiration: Total water loss combining surface water evaporation and plant transpiration.
    2. Evaporation: Phase change of liquid water into gas. It begins at 0°C (32°F) and boils at 100°C (212°F). Oceans, seas, lakes, and rivers supply ~90% of atmospheric moisture via evaporation. Evaporation increases with higher temperature, higher wind speed, lower humidity, and larger surface area.
    3. Transpiration: Release of water vapor into the air by plants, contributing ~10% of atmospheric moisture.
    4. Condensation: Vapor cooling into liquid droplets to form clouds when saturated air cools below dew point.
    5. Precipitation: Condensed droplets falling to Earth under gravity, depositing fresh water.
    6. Infiltration, Percolation, & Runoff: Water either moves across the land surface (runoff) or infiltrates through soil horizons and percolates deeper to replenish groundwater.

7. Water as an Energy Resource

  • Hydroelectricity (Hydel Power):
    • Generated from the potential energy of water falling from heights to spin turbine blades.
    • Clean, eco-friendly, renewable, and contributes roughly 7% of world electricity.
    • Leading producers globally are China and Canada.
  • Tidal Energy:
    • Renewable energy powered by the natural rise and fall of ocean tides via tidal streams, barrages, and tidal lagoons.
    • First tidal power station: La Rance (France); largest tidal power station: Sihwa Lake (South Korea).
    • Tidal Projects in India:
      • India’s first proposed plant is a 3 MW installation at Durgaduani Creek in the Sundarbans delta, West Bengal.
      • Identified potential sites for tidal power generation include the Gulf of Kutch and Gulf of Khambhat (Cambay) in Gujarat, and the Ganges delta in the Sundarbans.
  • Geothermal Water:
    • Heated groundwater and steam emerging in volcanic and fault areas create hot springs and geysers.
    • Promising Indian spots identified for geothermal power include Puga Valley in Ladakh and Manikaran in Himachal Pradesh.

8. Global Water Stress and Resource Depletion

  • Overpopulation has polluted most freshwater systems, leaving less than 1% of Earth’s fresh water readily accessible for human use.
  • Human activities such as over-exploitation, industrial pollution, and water acidification have severely endangered freshwater ecosystems, pushing millions of freshwater fish species toward extinction.
  • Water conservation measures outlined include checking pollution, recycling wastewater, constructing check dams and reservoirs, controlling population growth, and using water resources without depletion.

Types of natural vegetation of North America

(1) Tropical Evergreen Rain Forests,

(2) Deciduous or Monsoon Type of Forests,

(3) Dry Deciduous Forests and Scrubs,

Semi Desert and Desert Vegetation

In Northern America, the desert extends from Mexico into the USA. These deserts are called by different names. For example, It is called Mohave in the Sonoran, Californian, and Mexican deserts.

Annual Precipitation in Yuma, Arizona, in the United States receives 3.3 inches of rainfall in a year. The aridity of deserts is a significant feature of the desert climate.

These hot deserts lie on the back of the Horse Latitudes or the Sub-Tropical High-Pressure Belts. Here the air is descending, which is unfavorable for any precipitation.

The rain-bearing trade Winds blow offshore and the westerlies which are onshore blow outside desert limits.

The winds that reach the deserts blow from cooler to warmer regions lose their relative humidity, which makes condensation almost impossible. Also here there clear blue sky and scarcely any clouds.

In this region, the relative humidity is less than 30% and in these, every bit of moisture is evaporated and these regions do experience permanent drought.

(5) Tidal or Mangrove Forests and (6) Mountain Forests.

Factors affecting wind speed and direction Upsc

factors affecting wind speed

Due to atmospheric pressure, the air is set in motion. This is called Wind. This wind flows from a high-pressure area to low pressure area. Apart from the air pressure, the rotation of the earth also influences the rotation of the earth.

The force exerted by the rotation of the earth is called Coriolis force or effect. Altogether, the horizontal winds nearer to the surface of the earth are affected by the three forces combined such as the pressure gradient force, frictional forces, and the Coriolis force.

Also, the gravitational force acts downward.

Factors affecting speed and direction of wind Upsc
Factors affecting speed and direction of wind By Wagner Christian – Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=958801

Pressure Gradient Force

The force in the atmosphere is produced by differences in atmospheric pressure. The rate of change of pressure corresponding to the distance is called the Pressure Gradient. The Pressure gradient force causes the winds to blow.

The pressure gradient is strong when the Isobars are close and weak when the Isobars are far apart. That is, the wind blows from higher pressure to lower pressure, and also when there is a greater pressure difference, the greater is the wind speed.

The pressure gradient is perpendicular to an isobar. Also, the higher the pressure gradient, the more is the speed of the wind and also the higher is deflection in the direction of the wind. The velocity of the wind is directly proportional to the pressure gradient. That as the pressure increases a.k.a pressure gradient increases by which the speed of the wind also increases at the particular location.

The Pressure Gradient force is the one that triggers the initial movement of air.

Causes of Pressure Gradient Force

The difference in air pressure and pressure gradient is caused because of the unequal heating of the earth’s surface and the concentration of the incoming solar radiation at the equator. Also due to the energy surplus at low latitudes. Ex: Air is warm at the equator and Air is cold at the poles.

Frictional Force

The air is a fluid, the air molecules rub across the surface of the earth and the object over it such as hills, trees, etc. Also, the air above the surface faces little friction

Frictional forces influence the speed of the wind. The frictional force is greatest at the surface and it influences, generally to an altitude of 1 to 3 Km. The frictional force is minimal at the surface of the sea. Simply, the friction is greatest near the earth’s surface and it rapidly decreases with altitude or height.

The layer where the air is highly affected by the frictional force and the surface is called the boundary layer. The frictional force has two effects on the wind, first it opposes the direction of motion by acting opposite to the airflow, and second, it affects the speed of the wind.

The effect of friction is different on different terrains. On hilly terrains, winds are deflected by 30° or more. On the other hand on flat landforms, it is negligible.

Coriolis Force

Coriolis Force
Coriolis Force By Original: Brews ohareThis Version: CheChe – This file was derived from: Earth coordinates.PNG:, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=56454820

The direction of wind is affected by the rotation of the earth about the axis. This force due to the rotation of the earth is known as the Coriolis force.

As per the French Physicist Gustave-Gaspard Coriolis, who not that the Force due to the rotation of the earth, deflects the wind to the right direction in the Northern Hemisphere and to the left in the Southern Hemisphere.

Also observed, is that the deflection is more when the velocity of the wind is high. The Coriolis forces are directly proportional to the angle of latitude and are maximum at the poles and are absent at the equator.

This force acts perpendicular to the pressure gradient force. The wind blows in the low-pressure area.

In the equator, the Coriolis force is zero, and the wind blows perpendicular to the isobars. As result, the low pressure gets filled rather than getting intensified. Due to this tropical cyclones were not formed near the equator.

Pressure

The velocity and direction of the wind are the final output of the wind-generating forces. Above 2 to 3 km above the surface of the earth, the wind is free from the frictional effect of the surface.

In such heights, winds are affected only by the Coriolis forces and pressure gradient. If Isobars are straight and if there is no friction, the pressure gradient force is balanced by the Coriolis force and wind arises out of it blowing parallel to the isobar. This wind is called Geostrophic Wind.

The wind circulation around a low is called Cyclonic Circulation and around the high is called Anti Cyclonic Circulation. The Winds direction around such a system change as per their location in Southern Hemisphere or Northern Hemisphere.

Pressure SystemPressure condition at the CentreNorthern HemisphereSouthern Hemisphere
CycloneLowAnticlockwiseClockwise
AnticycloneHighClockwiseAnticlockwise
Wind Direction Pattern in Cyclones and Anticyclone

The wind circulation at the earth’s surface around low and high, on different occasions, is closely related to the higher-level wind circulations.

Convergence and divergence of wind Source: Ncert

Over the low-pressure area, the air converges and rises. In high-pressure areas, the air will subside from above and diverge at the surface. Apart from convergence, some eddies, convection currents, orographic uplift, and uplift along the fronts cause the air to rise. This is the basic need for the formation of clouds and precipitation.

Conclusion

In these notes, we have discussed the topic ‘Factors affecting speed and direction of the wind‘ in Physical geography and the areas covered are factors and outcomes due to the speed and direction of winds. This note is extremely useful for Upsc, Tnpsc, and other government service exams.

References

Atmospheric pressure and its variation Upsc

Atmospheric pressure

There is an uneven distribution of temperature, on the surface of the earth. This is because of the heating and as a result, the air expands and gets compressed on cooling.

Due to the compression and expansion of Air, variations occur in the atmospheric pressure. This variation in atmospheric pressure is the cause of the movement of air. The air moves from a high-pressure area to low pressure area.

The atmospheric pressure also determines, when will the air rise or sink. The heat and moisture are redistributed across the planet by Winds. As a result, Constant temperature is maintained on the whole planet.

The moist is raised vertically and gets cooled to form clouds, which brings down Precipitation in form of rain or snow.

Atmospheric Pressure

Every living being on the earth is subjected to air pressure. As one moves vertically, the air pressure gets varied and one gets difficulties in breathing.

Atmospheric Pressure is defined as “the weight of a column of air contained in a unit area from the mean sea level to the top of the atmosphere.” It is expressed in the units of Milibar.

Atmospheric Pressure a sea level is 1013.2 Milibar.

The air is denser at the surface of the earth and has higher pressure due to the effect of gravity.

Atmospheric pressure and its variation
Atmospheric Pressure across the world By William M. Connolley, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1447428

Mercury Barometer or the aneroid barometer is used to measure Air pressure.

The air pressure decreases with height and at any height or elevation, the air pressure varies from place to place and its variation is the main reason for the air motion.

As a result, the wind moves from high pressure to low-pressure regions.

Vertical Variation of Pressure

The pressure decreases rapidly with height, in the lower atmosphere. For each 10m elevation in height, the air pressure decreases by 1 Mb. This decrease in air pressure is not always constant throughout the world.

LevelPressure in MbTemperature in Celsius
Sea Level1013.2515.2
1 km898.768.7
5 km540.48-17.3
10 km265-49.7
Standard Pressure and Temperature at different levels of height

The vertical pressure gradient force is greater than the horizontal pressure gradient. But, the pressure gradient force is balanced by an equal but opposite gravitation force. As a result, we dot experience any strong upward winds.

Horizontal Distribution of Pressure

Horizontal Distribution of Pressure
Horizontal Distribution of Pressure By Hydrometeorological Prediction Center – http://www.wpc.ncep.noaa.gov/medr/day5nav.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=37193836

The small difference in pressure is high, important in determining the wind direction and its velocity.

The horizontal distribution of pressure is studied by drawing isobars at constant levels.

Isobars

It is a line on the map that connects points have same atmospheric pressure at a given time or average period.

In order to eliminate the effect of height (altitude) on pressure, it is measured at any station after being reduced to sea level for comparison.

As seen in the above image, the patterns of the isobars are related to the pressure systems.

The Low-pressure system is enclosed by one or more isobars with the lowest pressure in the centre. The high-pressure system is also enclosed by one or more isobars with the highest pressure in the centre.

World Distribution of Sea Level Pressure

Near the equator sea level, the pressure is low. This area is called Equatorial Low. Along 30° N and 30°, S has high-pressure areas. This area is called Subtropical Highs.

Along the poles, 60° N and 60° S, these low-pressure belts area is called Sub Polar Lows. Near the Poles, the pressure is high and these areas are called Polar High.

These pressure belts are not permanent as it oscillates with respect to the movement of the Sun. The pressure belts move southwards during the winter and move northwards during the summer in the northern hemisphere.

Conclusion

In these notes we have discussed, Atmospheric pressure and its variation, such as Vertical variation and horizontal distribution, and also its worldwide distribution, with its pressure levels and belts.

References

Major crops of Tamil Nadu and its primary cultivation region

Major crops of Tamil Nadu

Agriculture is and continues to be an important sector of Tamil Nadu’s economy. Around 60% of the total population of the state is engaged directly or indirectly in agriculture and its allied sectors. Tamil Nadu has around seven agro-climatic conditions and different soil conditions. That is suitable for the growth of Food crops, Species, Horticulture, Medicinal, and Aromatic plants.

But altogether, the major crop of Tamil Nadu is Paddy, millet, a variety of Pulses, different oil seeds, and Sugarcane. Also, different cash crops and tea plantations are also there.

Paddy

Rice field in Tamil Nadu By Jeevan naidu – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=62063761

It is the most important staple food crop of Tamil Nadu. The major variety of paddy grown in Tamil Nadu is Ponni and Kichadi.

Rice cultivation in the state is 3 Million Hectares. Paddy cultivation is concentrated in Thanjavur, Tiruvarur, Tiruvallur, Kancheepuram, Villupuram, Cuddalore, and Tirunelveli districts.

Tamil Nadu Ranks is third in India. The Cauvery delta of Thanjavur district (Undivided) is the major rice production region of Tamil Nadu. As a result, the Cauvery delta is called the Granary of Tamil Nadu.

Millets

Millet Cultivation in Tamil Nadu By Thamizhpparithi Maari – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17896698

Millets are stable food for 1/3 of the population of Tamil Nadu. Major millets are Sorghum/Jowar (Cholam), Ragi (Kezhvaragu), and Bajra (Kambu).

Millets are grown in drier areas as well as coastal plains. Sorghum is cultivated in the Coimbatore plateau and Kambam Valley.

Ragi is grown in cultivated Dharmapuri, Vellore, Coimbatore, and Cuddalore districts. Bajra is grown in Ramanathapuram, Tirunelveli, Karur, Perambalur and Salem Districts.

India observed 2018 as the National Year of Millets.

FAO decided to observe 2023 as the International Year of Millets.

Pulses

Pulses in Tamil Nadu By Monali.mishra – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=40862359

Pulses are the main source of protein in India for the Vegetarian Population. Major pulses grown in India are Bengal Gram, Black Gram, Green Gram, Cow Pea, and Horse Gram.

Pulses are grown mostly in drier regions with or without irrigation. A mild Cool Climate and low to moderate rainfall are optimal for Pulse cultivation.

It also serves as excellent fodder for animals. Pulses are grown in almost all the districts of Chennai, Nilgiris, and Kanyakumari.

Coimbatore tops in the production of Bengal Gram. Vellore and Kanyakumari district’s products are Red Gram.

Tiruvarur, Nagapattinam, and Thoothukudi districts are principal producers of green gram and black gram.

Horse gram is widely cultivated in Dharmapuri and Krishnagiri districts.

National Project On Organic Farming

To promote organic farming a central scheme named National Project on Organic Farming. The scheme provides financial assistance through a capital investment subsidy scheme.

Oil Seeds

Oil seed cultivation in Tamil nadu By I, Avenafatua, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2252388

Oilseeds grown in Tamil Nadu are Groundnut, gingelly, castor, coconut, sunflower, and mustard. The oil is used for cooking.

Industrial applications of oil are used for Lubrication and making Varnish, Soaps, Candle, cosmetics, pharmaceuticals,

Groundnut is a major oilseed of Tamil Nadu. Groundnut cultivation is concentrated in Vellore, Tiruvannamalai, Villupuram, Salem, and Pudukottai districts.

Groundnut is also grown in Dharmapuri, Cuddalore, Perambalur, and Madurai. Erode, Ramanathapuram, Sivagangai, and Virudhunagar districts are minor producers.

Coconut which is also used to produce Oil is grown in Coimbatore, Thanjavur, and Kanyakumari districts.

Sugarcane

Sugarcane cultivation in Tamil Nadu By Rufino Uribe – caña de azúcar, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=1155927

The major cash crop of Tamil Nadu is Sugarcane. It needs high temperatures and heavy rainfall.

Sugarcane grows well in tropical regions. Tiruvallure, Kancheepuram, Vellore, Cuddalore, Tiruchirapalli, Coimbatore, Erode, and Tirunelveli are major sugarcane-producing districts.

Cotton

Cotton cultivation in Tamil nadu By Azzurro – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1316365

Cotton is a fibre crop and it is also a cash crop. It requires black soil, long frost-free conditions, and warm and humid weather. It needs Humid weather in the early stages and hot, dry weather during the harvest period.

Cotton is mostly cultivated in the Coimbatore plateau and Vaigai-Vaippar river basins. It is also cultivated in Madurai, Ramanathapuram, Virudhunagar, Tirunelveli, Thoothukudi, Salem, and Dharmapuri districts.

Plantation crops

Plantation crops in Tamil Nadu By © 2011 Jee & Rani Nature Photography (License: CC BY-SA 4.0), CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=37837333

Major plantation crops of Tamilnadu are Tea, Coffee, Cashew, rubber, and Cinchona. In Tea production, Tamilnadu ranks second in area and production. First in tea production in Assam.

Tea plantations are found in the Hills of Nilgiris and Coimbatore. The Nilgiris is an important region for tea plantations.

Coffee plants are grown in the hills of Western and Eastern Ghats. Coffee plantations are found in the hilly slopes of the Dindigul, Madurai, Theni, and Salem districts.

Coffee plantations are also found minor on the slopes of Yercaud, Kolli Hills, and Kodaikanal. Tamil Nadu is second in coffee production in India. The first is Karnataka.

Rubber plantation is an important Plantation crop, concentrated in the Kanyakumari district. Pepper is another plantation crop that needs warm and wet slopes, so it is grown in the Eastern and Western Ghats of Tamil Nadu.

Cashew is largely cultivated in the Cuddalore district. Cinchona is planted at heights varying from 1060 to 1280 metres in Anaimalai Hills.

Cardamom estates are found in the hills of Madurai Regions at an elevation of 915 to 1525 metres.

TANTEA – (Tamil Nadu Tea Plantation Corporation Limited)

It is one of the largest Black Tea Producer in India with High-quality clonal tea. With a Plantation that spread over 4500 Hec.

Tamil Nadu Dairy Development Corporation Ltd

Tamil Nadu Dairy Development Corporation Ltd was transformed into Aavin that is Tamil Nadu Co-operative Milk Producers Federation Limited.

Conclusion

The major crops grown in Tamilnadu are rice, ragi, maize, pulses, sugarcane, etc.

* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.