Class 11 Geography (India: Physical Environment) Chapter 4 Climate

Key Concept: Seasonal Cycle

d) Retreating monsoon season

[Solution Description] The four main seasons recognized by Indian meteorologists are: cold weather season, hot weather season, southwest monsoon season, and retreating monsoon season. Thus, “Retreating monsoon season” is a correct answer.

Key Concept: Basic Definition

c) Human activities such as industrialization and burning of fossil fuels

[Solution Description] The primary contributors to global warming are human activities such as large-scale industrialization and the burning of fossil fuels. These actions release significant amounts of greenhouse gases into the atmosphere, which enhance the greenhouse effect and lead to an increase in Earth’s surface temperature.

Key Concept: Temperature Range Recognition

b) Low daily and annual range

[Solution Description] The tropical zone of India experiences high temperatures with very little daily and annual variation in temperature ranges.

Key Concept: Cyclone Formation, Cyclone Pathways

c) They often intensify and target the eastern coast of India, affecting regions such as the Godavari and Krishna deltas.

[Solution Description] Cyclonic depressions that form over the Andaman Sea usually move northwestward towards the Indian subcontinent. These systems gather moisture as they travel over warm sea surfaces, intensifying into tropical storms or cyclones. When these cyclones make landfall, especially targeting areas like the Godavari and Krishna deltas, they bring heavy rainfall and strong winds. In October, these cyclones can cause significant agricultural damage due to flooding and destruction of standing crops ready for harvest.

Key Concept: Crop Benefits

b) Rabi

[Solution Description] In North India, winter rainfall caused by temperate cyclones primarily benefits Rabi crops. These crops are generally sown in winter and harvested in spring, making them reliant on moisture from winter rainfalls to grow effectively.

Key Concept: Wind Circulation, ITCZ Influence

c) Enhances southwesterly moisture-laden winds

[Solution Description] The northward shift of the ITCZ during summer leads to the development of low-pressure areas over the northern plains. This results in the strengthening of the southwesterly monsoon winds over the southwestern regions of India. These moist-laden winds are drawn from the Indian Ocean and bring heavy rains to the coastal areas.

Hence, the shifting of the ITCZ affects the wind patterns significantly by drawing moisture-laden winds toward the mainland, contributing to the southwesterly monsoon.

Key Concept: Variability of Rainfall

a) Lack of rainfall

[Solution Description] Droughts are mainly caused by a deficiency in rainfall over an extended period, leading to a shortage of water.

Key Concept: Latitude and Altitude

b) Higher altitude

[Solution Description] Even though Agra and Darjiling share the same latitude, Darjiling is at a higher altitude than Agra. Higher altitudes typically have cooler temperatures due to thinner air which holds less heat.

Key Concept: Regional Temperature Comparison, Temperature Influence

c) Oceanic influence stabilizes temperatures in south India, preventing extreme highs.

[Solution Description] North-western India experiences extreme heat due to its continental location with little moderating oceanic influence. The region is predominantly landlocked, resulting in higher temperature extremes as heat is retained longer. In contrast, south India, being closer to oceans, benefits from sea breezes which moderate temperatures by absorbing and redistributing heat energy efficiently across the landmass. This leads to a more stable temperature range between 26°C and 32°C, avoiding extremes seen in more inland areas like north-western India.

Key Concept: Impact of monsoon variability on agriculture

a) Southwest Monsoon

[Solution Description] The primary climatic factor responsible for causing floods in India during summer is the southwest monsoon. This monsoon brings heavy rainfall, leading to excessive water accumulation and potential flooding in various regions.

Key Concept: Cyclonic Influence

d) Mediterranean Sea

[Solution Description] During the Shishira season, northwestern India is influenced by temperate cyclones originating from the Mediterranean Sea. These cyclones bring limited rainfall to regions such as Punjab and Rajasthan.

Key Concept: Sea Level Prediction

b) 48 cm

[Solution Description] According to the syllabus, the predicted rise in sea level by the end of the 21st century is 48 cm.

Key Concept: Break in the monsoon

c) Interruption in rainfall

[Solution Description] A “break” in the Indian monsoon refers to a period during the rainy season when the rainfall suddenly decreases or stops altogether over large parts of India. This phenomenon is caused by changes in the position of the monsoon trough and the easterly jet stream.

Key Concept: Cyclone Consequences, Monsoon and Economy

b) Destruction of crops and reduced yield.

[Solution Description] Cyclonic depressions often lead to excessive rainfall and flooding in eastern India, particularly impacting agricultural lands. This can destroy standing crops, leading to reduced yields and economic losses for farmers. The timing of these events during the harvest season exacerbates their negative impact on the economy.

Key Concept: Monsoon Dynamics, Break Variability

c) They allow winds to bypass the Ghats without lifting, leading to breaks in rain due to lack of upward motion.

[Solution Description] The Western Ghats run parallel to the west coast and are known for receiving heavy rainfall due to orographic lifting when moist air ascends the mountains. However, during a break in the monsoon, winds may blow parallel to the coastline without significant moisture-laden clouds being forced upwards, thus reducing rainfall. This geographical alignment can cause prolonged dry spells, particularly in the lee areas.

Key Concept: Monsoon and ITCZ Dynamics, Rain-shadow Mechanism

b) By shifting further north, enhancing wind convergence and increasing precipitation on the western slopes, intensifying the rain-shadow on the east.

[Solution Description] The ITCZ moves northwards into the Indian subcontinent during the summer months, bringing with it a zone of convergence where moist air masses from the Indian Ocean rise. When these moisture-laden winds encounter the Western Ghats, they ascend, causing precipitation on the western slopes. As the air descends on the eastern slopes, it loses moisture and warms, creating arid conditions — known as the rain-shadow effect. Thus, the northward shift of the ITCZ enhances this effect through increased wind activity.

Key Concept: Altitude Effect

a) Higher altitude

[Solution Description] Altitude affects temperature; higher altitudes generally have lower temperatures. Shimla is situated at a higher altitude compared to New Delhi, which results in cooler temperatures even though they are on similar latitudes.

Key Concept: Cyclone Impact Analysis, Rainfall Contribution

b) The geographical alignment funnels moist winds inland.

[Solution Description] Cyclonic depressions forming over the Andaman Sea move towards the east coast of the southern Peninsula. These systems bring in large amounts of moisture from the Bay of Bengal, leading to heavy and concentrated rainfall along this region. The geographical orientation of the eastern coast helps in funneling these moist winds which results in substantial precipitation, particularly impacting areas such as the Coromandel Coast.

Key Concept: Weather Elements

b) Hot monsoonal climate

[Solution Description] India’s climate is predominantly a hot monsoonal climate, which is common in south and southeast Asia. This type of climate is characterized by seasonal wind reversals and significant variations in temperature and precipitation across different regions of the country.

Key Concept: ITCZ Shift

c) It causes monsoon winds to blow from southwest to northeast

[Solution Description] When the ITCZ moves northward, it brings with it a shift in wind patterns. This results in the monsoon winds blowing from the southwest direction towards the northeast. This shift is responsible for bringing moist oceanic air into the Indian subcontinent, leading to monsoon rains.

Key Concept: Rain Shadow

a) Eastern side of Western Ghats

[Solution Description] The region located east of the Western Ghats is a rain-shadow area, meaning it receives low rainfall because the mountains block the monsoon winds.

Key Concept: Temperature Range

d) Below 21°C

[Solution Description] During the cold weather season in northern India, the mean daily temperature is generally below 21°C.

Key Concept: ITCZ Movement, Influence of Monsoon

d) Reduces winter rainfall in much of India

[Solution Description] During winter, the ITCZ shifts southward, away from India. This movement reduces the amount of moisture-laden winds reaching the subcontinent, directly impacting monsoon rainfall. As a result, there is a reduction in precipitation, which significantly impacts agriculture, water resources, and energy generation. Analyzing these impacts requires understanding atmospheric circulation and the role of the ITCZ in transporting moist air across regions.

Key Concept: Cyclone Formation Analysis, Cyclonic Depressions Impact

c) Warmer sea surface temperatures and lower air pressure

[Solution Description] The retreating monsoon results in a transition period where the southwest monsoon winds retract, leaving behind conditions conducive to cyclonic activity. Over the Bay of Bengal, this period is characterized by warm sea surface temperatures combined with low-pressure systems that can lead to cyclones. These conditions are prevalent due to the geographical positioning and atmospheric patterns during September-October.

Key Concept: Monsoon Mechanism

b) Differential heating of land and sea

[Solution Description] The monsoon mechanism involves the differential heating of land and sea. During summer, land heats up faster than the ocean, causing low pressure over the Indian subcontinent and drawing moist air from the ocean. In winter, the situation reverses, leading to high pressure on land and the flow of dry continental air outward.

Key Concept: Basic Effects

c) Carbon Dioxide

[Solution Description] Carbon dioxide ($CO_2$) is one of the primary greenhouse gases that absorbs longwave radiation and contributes significantly to the greenhouse effect, leading to global warming.

Key Concept: Sea Level Rise

b) Melting glaciers and sea-ice

[Solution Description] The main reason for the rise in sea level by the end of the 21st century is the melting of glaciers and sea-ice. This process contributes significantly to the increase in water volume in oceans, leading to a rise in sea levels.

Key Concept: Monsoon Importance

b) 64%

[Solution Description] According to the syllabus, 64% of India’s population is dependent on agriculture for their livelihood.

Key Concept: Temperature Range

b) 10°C-25°C

[Solution Description] During winter, central India typically experiences moderate temperatures due to its inland location and distance from the moderating effect of seas. The average temperature may vary between 10°C-25°C depending on specific locations.

Key Concept: Monsoon Dynamics, Temperature Influence

b) The increased rainfall reduces direct sunlight, lowering temperatures.

[Solution Description] The ITCZ is a zone near the equator where the trade winds converge. During the summer months, this zone shifts northward into the Indian subcontinent, bringing moisture-laden southwest monsoon winds. This northward shift leads to significant cloud cover and precipitation in the northern plains of India, causing a decrease in temperatures that were previously high due to intense solar radiation. Thus, the presence of these clouds and rain causes the temperature to drop.

Key Concept: Jet Stream Influence, Monsoon Withdrawal

b) It influences both onset and withdrawal by altering pressure gradients.

[Solution Description] The tropical easterly jet stream significantly affects the dynamics of the southwest monsoon. During onset, the development of the tropical easterly jet due to heating over the Tibetan plateau helps push the monsoon trough southwards, enabling the arrival of monsoon rains over the Indian subcontinent. For withdrawal, the weakening of the tropical easterly jet allows for the northward movement of the monsoon trough, signaling the retreat of the monsoon. This complex interaction highlights how atmospheric circulation patterns influence seasonal transitions.

Key Concept: Climatic Conditions, Environmental Impact

b) Soil erosion

[Solution Description] The Nor Westers bring thunderstorms that can have various effects on the environment. If their intensity increases unexpectedly, it may lead to severe weather conditions such as hailstorms or strong winds which could cause damage to agricultural crops like tea, jute, and rice. This increase in severity can result in soil erosion due to heavy rainfall and water runoff, thus impacting the fertility of the land.

Key Concept: Onset of Monsoon

b) Low pressure over the Indian subcontinent

[Solution Description] The differential heating of land and water creates a low-pressure area over the Indian subcontinent during summer. This attracts moisture-laden winds from the Indian Ocean, marking the onset of the southwest monsoon. The pressure gradient between the ocean and landmass is the driving force behind this climatic phenomenon.

Key Concept: Monsoon Dependency

c) 64%

[Solution Description] Approximately 64% of India’s agricultural land depends on monsoon rains as it provides critical water supply necessary for crop cultivation, especially in rain-fed areas.

Key Concept: Seasonal Transition, Monsoon Dynamics

b) The Aravalli Range aids in faster retreat due to lesser obstruction.

[Solution Description] During the transition period, the southwest monsoon starts retreating from northwestern India first because this region becomes cooler than the surrounding areas during the onset of autumn. The Aravalli Range plays a crucial role here; it doesn’t obstruct the retreating winds as effectively as the Western Ghats do for incoming monsoon currents. Therefore, changes in temperature gradient cause the shift in wind patterns, aiding the retreat of the monsoon.

Key Concept: Monsoon Dependency

b) 64%

[Solution Description] According to the syllabus, 64% of India’s population relies on agriculture, which is influenced by the southwest monsoon.

Key Concept: Rainfall Pattern

a) It reduces the need for irrigation.

[Solution Description] Winter rainfall from Western Disturbances provides essential moisture for the cultivation of rabi crops such as wheat, barley, and mustard in northwestern India. This timely rainfall supports soil fertility and ensures better crop yields.

Key Concept: Monsoon Withdrawal

d) September

[Solution Description] The monsoon generally begins to withdraw from the northwestern parts of India, including Western Rajasthan, around the month of September as the winds change direction.

Key Concept: Monsoon Trough

c) It enhances moisture convergence and rainfall

[Solution Description] The monsoon trough is an elongated low-pressure area that extends from the northwest to southeast across the Indian subcontinent during the monsoon season. Its presence enhances moisture convergence and uplift in the surrounding regions, which leads to increased cloud formation and rainfall. As moisture-laden winds from the ocean are drawn into this trough, they rise and cool, resulting in precipitation.

Key Concept: Rainfall Distribution and Rain-Shadow Regions

b) Descending warm winds that reduce cloud formation

[Solution Description] The rain-shadow effect occurs when moist air rises over a mountain range, cools, and loses its moisture before descending on the leeward side. As the air descends, it warms up, reducing relative humidity and cloud formation, leading to low rainfall in these regions.

Key Concept: Real-World Application, Complex Weather Patterns

c) The Eastern Ghats’ proximity affects the cyclones’ path and intensity as they make landfall.

[Solution Description] Cyclonic depressions during the retreating monsoon originate over the Andaman Sea and often move towards the Indian mainland. The Eastern Ghats play a critical role in modulating these systems. As these cyclones approach the coast, the topography can alter the path by deflecting or slowing down the system. Additionally, changes in terrain influence the distribution and intensity of rainfall associated with these cyclones, impacting regions like Tamil Nadu.

Key Concept: ITCZ Role

d) Encourages the development of thermal low over north and northwest India

[Solution Description] The ITCZ’s northward shift during summer results in the convergence zone moving over the Indian subcontinent. This helps draw warm, moist air masses from the ocean into the land, encouraging the development of a thermal low and enhancing monsoon activity.

Key Concept: Real-world Application, Climate Change Impact

c) It may increase the intensity and frequency due to urban heat island effects.

[Solution Description] Increasing urbanization in Delhi can lead to more heat retention due to concrete structures and reduced vegetation, potentially intensifying the ‘Loo’ winds. Additionally, urban heat islands may form, leading to localized low-pressure areas that could alter wind patterns. This might cause an increase in both the occurrence and severity of the ‘Loo’ winds.

Key Concept: Rainfall Variation

c) Parts of Karnataka

[Solution Description] Inadequate rainfall areas receiving below 50 cm include parts of Andhra Pradesh, Karnataka, and Maharashtra.

Key Concept: Impact of Climate Change

c) Increased flooding in coastal regions

[Solution Description] Rising sea levels, primarily caused by melting glaciers and sea ice, lead to increased flooding in coastal regions of India.

Key Concept: Temperature Variation

d) Himalayas

[Solution Description] The Himalayas act as a significant climatic barrier for the Indian subcontinent. Their towering presence blocks the icy winds coming from Central Asia, thereby preventing extreme cold temperatures in much of northern India during winter.

Key Concept: Snowfall Regions

d) Himalayan region

[Solution Description] Snowfall in India is mainly confined to the Himalayan region due to its high altitude, where temperatures are low enough for snow formation.

Key Concept: Monsoon Mechanism

d) The pressure difference between Tahiti and Port Darwin

[Solution Description] The intensity of the southwest monsoon winds is determined by the pressure difference between Tahiti and Port Darwin. This pressure difference affects the flow of winds in the Indian Ocean region, influencing the strength of the monsoon.

Key Concept: Rainfall Distribution

c) Odisha

[Solution Description] According to the syllabus, the northeastern Peninsula includes areas like Odisha, Jharkhand, and Bihar where medium rainfall between 100-200 cm is received.

Key Concept: Latitude Influence

b) South of the Tropic of Cancer

[Solution Description] The Tropic of Cancer divides India into two parts: the northern part lies in the temperate zone and the southern part lies in the tropical zone. Areas south of the Tropic of Cancer experience a tropical climate due to their location closer to the equator.

Key Concept: Regional Variations

b) Northern India

[Solution Description] In the Hemanta season, northern regions of India generally experience the most significant drop in temperature. This is due to the geographic location and reduced solar heating as winter approaches.

Key Concept: Cyclone Formation, Rainfall Anomalies

b) Reduced rainfall leading to drought-like conditions

[Solution Description] Cyclonic depressions originating over the Andaman Sea typically move towards the eastern coast of India, bringing heavy rainfalls during the retreating monsoon to regions like Tamil Nadu. The absence of such depressions would likely lead to significantly less rainfall compared to normal levels, affecting water resources, agriculture, and overall weather patterns in the region.

Key Concept: Regional Climate Variations

d) The Thar Desert

[Solution Description] The Thar Desert, located in Rajasthan, is known for its high temperatures due to its desert climate and receives very little rainfall annually.

Key Concept: Role of Himalayas

c) By acting as a barrier to cold winds and trapping monsoon winds

[Solution Description] The Himalayas play a critical role in influencing India’s climate by acting as a barrier to cold winds from Central Asia, thereby maintaining a relatively warmer temperature in northern India. They also help trap monsoon winds, leading to precipitation over large parts of the country.

Key Concept: Rainfall Impact

b) Northwestern India

[Solution Description] Regions like Punjab, Haryana, Delhi, and western Uttar Pradesh receive winter rainfall due to the influence of Westerly Jet Streams.

Key Concept: Westerly Jet Streams

c) They guide the monsoon depressions towards India

[Solution Description] Westerly jet streams are fast-flowing, narrow air currents in the atmosphere that can steer weather patterns. During winter, they flow across the Indian subcontinent but retreat northward during the summer, allowing the easterly jet stream to strengthen and facilitate the northward penetration of the southwest monsoon.

Key Concept: Temperature Shield

b) They block cold northern winds from entering India

[Solution Description] The Himalayas block the cold northern winds coming from near the Arctic Circle, thereby preventing these winds from entering India and influencing its climate.

Key Concept: Monsoon Trough

c) It encourages rainfall by directing moist winds

[Solution Description] The monsoon trough is an elongated low-pressure area that extends from the northwest to the southeast of India. It acts as a conduit for moisture-laden winds, encouraging precipitation along its path and thus influencing the distribution of rainfall significantly.

Key Concept: Temperature Extremes

c) Bhopal

[Solution Description] Regions that are far from the coast do not benefit from the sea’s moderating effects. This results in wider fluctuations between high and low temperatures. Bhopal, being located inland, would be expected to experience more severe temperature extremes compared to coastal areas.

Key Concept: ITCZ Shift, Monsoon Variability

d) It leads to frequent dry spells in northern India

[Solution Description] The northward shift of the ITCZ generally corresponds to the movement of moist air masses into northern India, enhancing rainfall activity. Normally, when the ITCZ is positioned over a region, it brings low-pressure conditions conducive for rain-bearing systems. However, if it shifts too far north, away from the typical position above central or northern India, it can result in breaks in monsoon rainfall due to lack of moisture-laden winds. This occurrence reduces the frequency and intensity of rain-bearing storms along the monsoon trough, leading to dry spells.

Key Concept: Monsoon Importance

c) Monsoon

[Solution Description] Monsoon is critical for agriculture in India since it provides the majority of the water needed for crop growth. It affects the timing and productivity of planting seasons, making it the central axis of the country’s agricultural cycle.

Key Concept: Monsoon Impact

c) Central and North-Western India

[Solution Description] El-Nino typically results in warmer sea surface temperatures in the Pacific Ocean, which can negatively impact the Indian monsoon by changing wind patterns and reducing rainfall over certain regions. Historically, Central and North-Western India are significantly affected due to a reduction in rainfall.

Key Concept: Rain-shadow Effect, Monsoon and Agriculture

d) Western Ghats obstructing wind flow.

[Solution Description] The Western Ghats are a significant mountain range that runs parallel to India’s western coast. When the monsoon winds blow from the southwest, they rise against the Western Ghats, causing precipitation on the western side. As the winds descend on the eastern side, they lose most of their moisture, leading to a rain-shadow effect. This results in drier conditions in regions lying east of the Western Ghats, such as parts of Karnataka and Andhra Pradesh, affecting agricultural productivity due to reduced rainfall.

Key Concept: Cyclone Path Analysis, Monsoon Withdrawal Sequence

a) 1) Northwest India, 2) Bay of Bengal, 3) Eastern Coastline, 4) Southern Peninsula

[Solution Description] The monsoon withdrawal typically starts from northwest India by early September and gradually retreats southwards. Cyclones formed in the Bay of Bengal often move towards India’s eastern coast, impacting regions like Odisha and Andhra Pradesh. Therefore, a correct sequence could be:

1) Northwest India (retreat begins),

2) Bay of Bengal (cyclones form),

3) Eastern Coastline (cyclone impacts),

4) Southern Peninsula (monsoon ends).

Key Concept: Coriolis Effect

d) It deflects them to the south

[Solution Description] As trade winds from the Southern Hemisphere cross the equator, the Coriolis effect comes into play due to the Earth’s rotation. In the Southern Hemisphere, moving objects are deflected to the left, and when these winds cross into the Northern Hemisphere, they are deflected to the right, which results in them blowing from southwest to northeast. This deflection forms the basis for the southwest monsoon winds.

Key Concept: Agricultural Impact

c) Barley

[Solution Description] During the Vasanta season, wheat is typically harvested rather than sown. On the other hand, rice sowing begins after Vasanta as it requires the monsoon rains for growth. Barley and maize are two crops that can be sown around this time, but barley is more commonly associated with Vasanta due to the suitable climatic conditions.