Climate

India has a tropical monsoon type of climate. Two factors responsible for this type of climate are-

1. The Himalayas
2. Varied Relief

Two important characteristic features of the Monsoon rainfall in India are-

1. Reversal of wind system.
2. Uneven distribution of rainfall over the year.

(i) The Northern Plains of India experience heatwaves at the end of April due to several geographical reasons. During this time, the Sun starts moving northward, increasing the intensity of solar radiation over the region. The clear skies, dry land surface, and continental type of climate cause rapid heating. In addition, hot, dry winds called Loo blow across the plains, further raising the temperature and leading to heatwave conditions.

(ii) Tropical cyclones are more common in the Bay of Bengal than in the Arabian Sea because the Bay of Bengal is surrounded by land that traps heat. Due to this, the Bay of Bengal has warmer sea surface temperatures, which provide more moisture and energy for cyclone formation.

(iii) The Indo-gangetic plain gets some rainfall in the month of December and January because of the Western Disturbances, which originate in West Asia and in the regions near the Mediterranean sea. These westerly depressions bring winter rainfall over the Indo-Gangetic Plains.

(i) Monsoon are periodic or seasonal reversing winds. They are divided into two wind systems — the Summer Monsoon that blow south-west and the Winter Monsoon that blow north-east.

(ii) Cherrapunji and Mawsynram in Meghalaya receive the heaviest rainfall.

During the winter season, Punjab receives rainfall from temperate cyclones that originate from the Mediterranean Sea. These cyclones are not of great intensity. Tamil Nadu receives rainfall from the north east monsoon winds that blow over the Bay of Bengal and bring winter rainfall to the state.

A rain shadow area is an area of dry land that lies on the leeward side of a mountain. High mountains act as barriers for cold if they are high enough and lie in the path of rain – bearing winds. The leeward side of the mountains remains dry.

The western ghats in India are an example of mountains causing rain shadow area. The moisture laden winds from the Arabian Sea branch shed most of its moisture on the western slopes of the western ghats due to which by the time they reach the eastern slopes of western ghats the winds have less moisture and this side receives very less rainfall. For example, Mahabaleshwar situated on the Western side of western ghats, receives 250 cm of rainfall whereas Pune, only a few km away, receives less than 70 cm of rainfall.

(i) The annual rainfall experienced by the station is 114.3 cm.

(ii) The station experiences Maritime climate. This is because this station experiences moderate climate with not extreme temperature variations between summer and winter.

(iii) The season during which rainfall is the heaviest is retreating monsoon. A probable station that satisfies this criteria is Chennai in Tamil Nadu.

(i) Western Rajasthan receives no rain from the Arabian Sea branch of the South-West Monsoon winds because the Arabian Sea branch of the South west monsoon blows parallel to the Aravali hills. Since the moisture-bearing winds do not strike the mountains, they do not cause any rainfall in Western Rajasthan.

(ii) Mangalore is situated along the Western Coast of India. Therefore, it experiences moderate impact of land breezes and sea breezes all through the year. This keeps the weather of Mangalore moderate i.e. neither too hot nor too cool. Hence, it is not cold even in the month of December.

(iii) Shimla is cooler than Delhi in summer because it is located at a higher altitude than Delhi and the temperature decreases with the height at a rate of 1°C for every 166 m of ascend.

Two points of difference in climate between the northern and the southern zone of India due to latitude are —

1. The northern zone has cold winter season and hot summer season while the southern zone is warmer than the north but does not have a clear-cut winter season.
2. The northern zone doesn't have the mid day sun almost vertically overhead during any part of the year, while the southern zone has the mid day sun almost vertically overhead at least twice a year.

The water bodies have a great impact on the climate in coastal areas. Water bodies act as a major source of moisture to the summer monsoons and bring heavy rainfall to the whole area. Such areas experience moderate climate, neither too hot nor too cold.

(i) India has a varied climate due to the presence of various relief features like mountains, deserts, presence of seas etc. Further the large latitudinal extent, altitude, presence of many mountain ranges and nearness to the oceans results in different climatic conditions in different regions.

(ii) Most parts of India receive rainfall between June and September because the differential heating of land and sea during summer season causes the monsoon winds to drift towards the subcontinent.

(iii) South-West Monsoon withdraw from northern India in October because the monsoon trough of low pressure over the Ganga plains becomes weaker due to the apparent southward movement of the sun. The low pressure trough is gradually replaced by high pressure.

(i) Jet streams are cold fast blowing winds that develop in the upper layers of the atmosphere.

(ii) They influence the climate of India as the westerly jet stream prevails over the North Indian Plains during the winter months, while the easterly jet stream steers the tropical depression over India. These depressions play a significant role in the distribution of monsoon rainfall in the subcontinent. The highest rainfall occurs along the track of these depressions.

El-Nino increases the surface temperature of the sea and affects the movement of monsoon winds in the Indian Ocean and causes weak drought-like situation in the Indian sub continent.

Two characteristic features of North-East Monsoon are-

1. These winds blow from December to February.
2. These winds blow from land to sea.

Three important features of rainfall in India are-

1. There is rainfall over three months and the rest of the year is mostly dry. Seventy percent of annual rainfall occurs in the rainy season.
2. The rains are mainly of relief type. The windward slopes of the mountains get more rainfall than the leeward side.
3. Only a small portion of the rainfall is received from sources other than the monsoon, like cyclonic rainfall and convectional rainfall.

(i) Pune receives less rainfall than Mumbai because Mumbai lies on the windward side of the Western Ghats while Pune lies on the leeward side. Since places lying on the leeward side receive less rainfall, Pune receives less rainfall than Mumbai.

(ii) A tropical cyclone is mainly formed due to the development of a low pressure area over the sea, this results in high humidity and temperature which causes heavy rainfall. However, in a temperate cyclone wind speed is low and all sectors of the cyclone have different temperatures which is followed by continuous light rainfall for many days.

(iii) Kerala has a tropical climate while Bihar has a continental climate because Kerala is situated near water bodies while Bihar is situated in the interior of the subcontinent. Influenced by the sea, Kerala experiences maritime climate, neither too hot nor too cold while Bihar experiences continental type of climate, very hot in summer and very cold in winter.

(i) Western Disturbances — A characteristic feature of the cold weather season is the inflow of depressions from the west and the north-west. These low pressure systems are called western disturbances. They originate in West Asia and the regions near the Mediterranean Sea. They travel eastwards across Iran and Pakistan and reach India during the winter season. They bring the much needed winter rains over the plains and snowfall in the mountains.

(ii) Mango Showers — Mango showers are the pre-monsoon showers in the Indian states of Karnataka, Kerala, Konkan and Goa that help in the ripening of mangoes. These showers are also important for tea and coffee plants.

(i) The monsoon rain is unevenly distributed over India because most parts of India receive relief rainfall, therefore windward sides always receive more rainfall than the leeward side. Some places like Aravali and Coromandel coast lie parallel to south west monsoon winds, hence, are not able to obstruct these wind and receive very little rainfall.

(ii) Excessive cold in north India during winter season because north India is far from the sea and the equator. Hence, it experiences continental type of climate — cold winters and hot summers.

(iii) Most of the India remains dry during the North-East Monsoon season because north-east trade winds blow from land to sea and hence, do not carry moisture necessary for rainfall.

(i) Tamil Nadu and Rajasthan get very little rain from the Summer Monsoon.

(ii) Two local winds which blow in India during the summer season are Loo and Kalbaisakhi.

During the months of October-November, the south-west monsoon winds become weaker and start to retreat from the skies of North India. This phase of the monsoon is known as the retreating monsoon.

Retreating Monsoon rain is experienced in the months of October and November.

(i) The northern plains of India do not freeze in winter because the Himalayas form a climatic barrier separating the Indian subcontinent from the rest of Asia. They prevent the cold Siberian winds from entering India.

(ii) The state of Rajasthan receive scanty rainfall because it lies in the rain-shadow region of the Aravali Mountains. The Aravali Hills run parallel to the Arabian Sea branch, and thus do not form any barrier to intercept the winds. The winds thus passes through Rajasthan without causing any rainfall.

(iii) Chennai is located on the Coromandel Coast (Tamil Nadu) and receives most rainfall from the Northeast Monsoon and the Retreating Monsoon. Bengaluru, located inland in Karnataka, primarily receives rainfall from the Southwest Monsoon. Hence, Chennai has more wet days than Bengaluru.

(i) The North-East Trade Winds dominate during the winter season.

(ii) North-east trade winds blow from land to sea, hence, most parts of the country remain dry. These winds may cause some amount of rainfall on the Coromandel coast. The nights are extremely cold while the days are pleasantly warm.

The eastern coast of Tamil Nadu and Andhra Pradesh receives much rainfall during the winter season through north-east monsoons.

(i) The western part of Rajasthan is a desert because the Aravali range lies parallel to the moisture laden winds coming from the Arabian Sea. Since they do not obstruct the winds, it does not rain in western Rajasthan.

(ii) Kochi has a coastal location while Agra is located away from the sea. Due to the influence of the moist winds from the sea, Kochi experiences a moderate climatic condition throughout the year whereas Agra has extreme temperature conditions resulting in high annual range of temperature than Kochi.

(iii) The Northern plains and Punjab receive winter cyclonic rain in winter due to the western disturbances entering the Indian sub-continent from the North-west.

(i) North East Trade winds cause the winter rain along Coromandel coast.

(ii) Tamil Nadu gets sufficient rainfall from the winter monsoon.

An interschool Football Match at Vishakapatnam from November 1 to 3 had to be cancelled because of the cyclones. This is a season of retreating monsoon. During this season the low pressure conditions of the land are transferred to the centre of the Bay of Bengal that gives rise to cyclonic depressions.

(i) Kanyakumari experiences equable climate because it is located near the coast, and there is not much difference between the temperatures during the summer and winter.

(ii) The Coromandel Coast remains dry in July and August because it lies in the rain-shadow region of the Arabian Sea branch of the Southwest monsoon. Also, the Bay of Bengal branch of the monsoon flows almost parallel to the coast, so it does not bring much rain to this region during this time.

(iii) Mangalore lies on the windward side of Western Ghats and Mysore lies on the leeward side of the Western Ghats. Since areas located on the windward side receive more rainfall than the areas located on the leeward side, Mangalore experiences more rainfall than Mysore.

(i) Tamil Nadu gets rainfall from the Retreating Monsoon.

(ii) Meghalaya and Arunachal Pradesh get more than 200 cm of rainfall in India.

Winter showers in Western Uttar Pradesh and Punjab originate from the weak temperate cyclones from the Mediterranean Sea.

Kalbaisakhis are of economic importance in West Bengal and Assam because they bring rainfall in these regions. This rainfall is quite beneficial for growing jute and rice in West Bengal and tea in Assam.

(i) Since Thiruvananthapuram lies on windward side of Western ghats therefore it receives heavy rainfall from South West monsoon while Chennai lies on the leeward side and gets rainfall from North East monsoon which is not as strong. Thiruvananthapuram also gets some rain from the retreating Monsoon.

(ii) Cherrapunji lies on the crest of the southern range of Khasi hills. It receives rain from the South West Monsoon Bay of Bengal Branch as it is in the pathway of these winds. Hence, it receives heavy rainfall. Shillong is located on the upper (leeward) side of the Garo-Khasi-Jaintia hills, which is a rain shadow area and hence, receives less than 200 cm of rainfall in a year.

(iii) Jaipur has a higher annual range of temperature than Goa because Jaipur is situated in the northern part of India, away from the sea. Hence, Jaipur experiences continental type of climate, too hot in summer and too cold in winter. Goa, on the other hand, is situated near the sea so it has a moderate type of climate, neither too hot nor too cold.

(i) The Himalayas form a climatic barrier separating the Indian subcontinent from the rest of Asia. They prevent the cold Siberian winds from entering the Indian region and from India becoming a cold desert.

(ii) During the South West Monsoon season, the Himalayas play an important role in determining the amount of rainfall received by several places in the country. They act as a barrier to the South West Monsoon winds coming from the Indian Ocean. These winds when strike the mountains bring rainfall to the northern plains.

El-Nino refers to an abnormal warming of surface waters in the equatorial Pacific region. It increases the surface temperature of the sea and affects the movement of monsoon winds in the Indian Ocean.
The expected date for the onset of Southwest Monsoons over Kerala is June 1.

This pattern of rainfall is different from the regular monsoon pattern in India. Normally, the Southwest monsoon sets in by early June and brings steady rainfall through June to September. Rainfall is usually well-distributed during these months.

However, in the year mentioned, rainfall was below average in June, unusually high in July, and almost dry in August. This uneven distribution can affect agriculture and water availability, as crops need regular and timely rain.

The difference is highlighted in the table below:

(i) The southern hills of Assam lie directly in the path of moisture-laden winds of Bay of Bengal branch of the South-west Monsoon. Hence, most of their moisture is shed over the southern hills and these winds become drier as they move northward. This creates a rain-shadow effect, leading to less rainfall in the northern hills of Assam.

(ii) Northern India has cold-wave conditions in January due to cold, dry northeast monsoon winds. A high-pressure area forms over Central Asia and northwest India, while a low-pressure area lies over the Indian Ocean. Winds blowing from land to sea bring cold, dry weather, and cold winds from the Caspian Sea and Turkmenistan lower temperatures further.

(iii) The month of October is marked by sultry and humid weather because the Southwest monsoon begins to retreat from northern India. Although the skies start to clear and night temperatures drop, the land remains moist after the rains. The combination of high day temperatures and moisture in the air give rise to sultry humid weather in October.

(i) City A annual rainfall = 1156 mm
    City B annual rainfall = 1036 mm

(ii)

City A

Upon analyzing the temperature and rainfall patterns of City A, Delhi closely matches the provided data.

Reasons:

1. The climatic data of city A indicates a region with a continental climate, characterized by cool winters, warm summers, and a pronounced monsoon season with significant rainfall during the summer months.
2. Heavy rainfall experienced from the South west monsoon, with peaks in July-September.
3. Almost no rainfall from November to April.

City B

Upon analyzing the temperature and rainfall patterns of City B, Bengaluru (Bangalore) in Karnataka closely matches the provided data.

Reasons:

1. This city experiences moderate temperatures throughout the year with no extreme cold, indicating a Maritime climate.
2. Due to South-west monsoon, the rainfall increases from June, peaking between July and October, and tapering off by November.

The Bay of Bengal branch of the South-west monsoon is directed towards the coast of Myanmar and part of south-east Bangladesh. However, owing to the presence of the Arakan Hills along the coast of Myanmar, a large part of this branch of monsoon is deflected towards the Indian subcontinent. The monsoons, therefore, enter West Bengal from south and south-east instead of the south-westerly direction.

The Great Indian Desert (Thar Desert) plays a vital role in the monsoon mechanism by heating up during summer and creating a strong low-pressure area that attracts moisture-laden southwest monsoon winds. Without it, this low pressure would be weaker, reducing monsoon rainfall in northern and northwestern India. The Thar Desert also cools quickly after summer, helping in the early withdrawal of monsoons by reversing wind patterns. Its absence could lead to irregular monsoon withdrawal and weaker rainfall, affecting agriculture and the overall climate of the region.

Most parts of India do not receive rainfall in the winter season because during this time, the winds blow from the land to the sea (northeast monsoon winds). Since these winds originate over the land and have anti-cyclonic circulation, they are dry and do not carry much moisture. As a result, they do not cause significant rainfall in most parts of the country.

Two regions that receive winter rainfall are:

1. Punjab — Punjab receives rainfall from Western Disturbances (temperate cyclones) that originate from the Mediterranean Sea.
2. Tamil Nadu — Tamil Nadu receives rainfall from the North East Monsoon Winds. These winds pick up moisture while blowing over the Bay of Bengal and bring rainfall to Tamil Nadu.

India's economy is primarily agriculture based. A good Southwest Monsoon significantly impacts India's economy by enhancing agricultural productivity in following ways:

1. A good southwest monsoon brings enough rainfall for healthy crop growth.
2. It improves agricultural output, which benefits farmers.
3. Increased rural income boosts demand for goods and services.
4. Food prices stay stable or fall, reducing inflation.
5. Industries linked to farming, like food processing, also grow.
6. Contributing 14% to the national GDP, agriculture supports millions and good monsoon boosts agriculture which in turn improves the overall economy.

The surplus rainfall in regions like Rajasthan, Gujarat, Tamil Nadu, and Goa can have both positive and negative geographical impacts:

Benefits of Surplus Rainfall

1. Groundwater Recharge – In arid and semi-arid regions like Rajasthan and Gujarat, excessive rainfall helps recharge groundwater tables and fills reservoirs, reducing water scarcity.

2. Agricultural Productivity – Increased rainfall enhances soil moisture, benefiting rain-fed crops like millets, pulses, and cotton in Gujarat and Rajasthan.

3. Reservoir and River Replenishment – In Tamil Nadu and Goa, monsoon-fed rivers like the Cauvery and Mandovi receive more water, supporting irrigation and drinking water supply.

4. Hydropower Generation – Dams such as the Sardar Sarovar Dam in Gujarat and Mettur Dam in Tamil Nadu can store surplus rainwater, increasing hydropower production.

Challenges of Surplus Rainfall

1. Flooding and Waterlogging – Rajasthan and Gujarat, with their low drainage capacity, can experience flash floods, affecting settlements and infrastructure.

2. Soil Erosion and Landslides – In Goa and Tamil Nadu, heavy rainfall can trigger coastal erosion and landslides, particularly in hilly areas like the Western Ghats.

3. Crop Damage – Excessive rainfall can lead to waterlogging in paddy fields in Tamil Nadu and spoil harvested crops.

Thus, while surplus rainfall enhances water availability, its impact varies based on topography, land use, and drainage systems in each region.

Regions experiencing a rainfall deficit face severe geographical challenges due to reduced water availability, agricultural distress, and ecological imbalances.

Example: Bihar (-26% Rainfall Deficit)

1. Impact on Agriculture: Bihar relies heavily on the Southwest Monsoon for its kharif crop cultivation, particularly paddy (rice). A 26% deficit means lower soil moisture, affecting sowing, crop growth, and yields.

2. Reduced Groundwater Recharge: Lower monsoon rainfall leads to less infiltration into aquifers, worsening water scarcity in districts dependent on wells and tubewells for irrigation.

3. Drought-Like Conditions: Parts of south and central Bihar, which already receive less rainfall compared to the flood-prone north, may experience drought-like conditions, impacting food security.

Thus, states facing monsoon deficits experience agricultural setbacks, water shortages, and ecological imbalances, requiring efficient water management strategies to mitigate long-term impacts.

The image depicts urban flooding, where a man is navigating a waterlogged road.

Causes of the Calamity:

1. Heavy Rainfall Due to Monsoon: Intense rainfall, especially during the Southwest Monsoon (June-September), can overwhelm drainage systems, leading to water stagnation on roads.
2. Poor Drainage and Urbanization: Encroachment of natural drainage channels, excessive concretization, and lack of proper stormwater drainage result in inefficient water runoff.
3. Low-Lying Area and Poor City Planning: Some cities are located in low-lying flood-prone areas, where water accumulates easily, causing flooding.
4. Clogging of Drains: Accumulation of garbage and plastic waste in drains prevents water from flowing, worsening waterlogging conditions.

Measures to Bring Relief:

1. Improving Drainage Systems: Cleaning and maintaining storm water drains to ensure smooth water flow and constructing underground drainage systems in flood-prone urban areas.
2. Sustainable Urban Planning: Developing permeable surfaces like parks and green belts to allow water absorption, and preventing illegal construction that blocks drainage pathways.
3. Early Warning Systems: Implementing weather forecasting and flood alert systems to prepare in advance.
4. Public Awareness and Waste Management: Educating citizens about responsible waste disposal to prevent drain blockages.

By addressing urban planning, waste management, and drainage efficiency, cities can reduce flooding and minimize disruptions caused by heavy rainfall.

(i) Western Disturbances are the cause for the precipitation to occur at Nainital.

(ii) During winter, western disturbances bring moist winds to northern India. In high-altitude regions like Nainital, low temperatures cause this moisture to condense and fall as snow instead of rain.

(i) The local wind being discussed is called 'Loo'.

(ii) The Loo is a hot, dry local wind that blows over northern India in May. It raises temperatures in Lucknow to over 45°C, causing extreme heat. This makes afternoons unbearable, forcing people to stay indoors to avoid heat-related illnesses.

windward slope

Both A and R are true and R is the correct explanation of A.

Explanation — India has a tropical monsoon type of climate because India lies in the tropical belt and its climate is influenced by the monsoon winds which are largely confined to the Tropics.

it lies in the way of South West Monsoon winds.

Retreating monsoon

Both A and R are true and R is the correct explanation of A.

Explanation — The Himalayas, due to their great height, act as a climatic barrier preventing cold winds from Central Asia, thus influencing the climate of the Indian subcontinent.

Retreating monsoon

Urbanisation

A is true but R is false.

Explanation — Western Ghats lie not parallel but perpendicular to the direction of the moist South-West Monsoon winds. These winds go up the slopes of the Western Ghats, become cool and bring heavy rainfall on the western side.

Winter

South-West

Coromandel coast and Odisha.

Break of monsoon

Kalbaisakhi

In Punjab and Haryana

High temperature and humidity

Both A and R are true and R is the correct explanation of A.

Explanation — The monsoon rains begin in June–July, bringing relief from the summer heat and causing a significant drop in temperature in Nagpur.

Because they lie in the rainshadow of the Eastern Ghats.

Monsoon winds

Northward migration of the Sun from the equator.

Both A and R are true and R is the correct explanation of A.

Explanation — Due to the presence of the Arakan Hills along the coast of Myanmar, a large part of the Bay of Bengal Branch of the South West Monsoon is deflected towards the Indian Subcontinent.

October

Kerala

East Coast of India