Class 9 Geography Chapter 1 Question Answers - Contemporary India - I

Q1. Write a brief note on the south-west monsoon and its influence on the climate of India. (Important)

Ans: The south-west monsoon is a vital weather phenomenon in India, characterised by a significant shift in wind patterns during the summer months. Here are the key aspects of its influence on India's climate:

• The term "monsoon" comes from the Arabic word mausim, meaning season.
• It typically begins in early June, peaks by mid-July, and lasts until mid-September, bringing about 100-120 days of rainfall.
• A low-pressure area forms over northern India, attracting southeasterly trade winds from the Southern Hemisphere.
• The monsoon consists of two main branches: the Arabian Sea branch and the Bay of Bengal branch, which converge over the Northern Plains.
• Rainfall is uneven, with heavy precipitation in the West Coast and Northeast, while regions like Rajasthan receive less.
• The monsoon is marked by alternating wet and dry spells, known as breaks, which can lead to flooding in some areas and droughts in others.

Q2. Why does the rainfall decrease from east to west in Northern India? Write a brief note explaining why. (Important)

Ans:  India receives most of its rainfall from the southwest monsoons, which have two branches:

• Arabian Sea Branch: Brings rain to western coastal areas and the Northern Plains by July.
• Bay of Bengal Branch: Reaches northeastern states like Assam by June, causing heavy rainfall in the eastern Northern Plains. Moisture decreases as winds move westward, reducing rainfall.

Topographical Effects:

• The Purvanchal Hills deflect winds, causing heavy rain in the east.
• The Aravalli Hills, running parallel to monsoon winds, result in minimal rainfall in western Rajasthan.
• The Himalayas force winds to rise, increasing rainfall in the central and eastern plains.

Monsoon Trough:
Rainfall is abundant in the plains when the trough lies over them but decreases when it shifts north, causing dry spells in the plains and heavy rains in the mountains.

Q3. Distinguish between southwest monsoon and northeast monsoon. (CBSE 2010)

Ans: The monsoon climate features a significant change in wind direction with the seasons. Here are the main differences between the southwest monsoon and the northeast monsoon:

• Direction and Timing: The southwest monsoon blows from the south-west towards the Indian mainland from June to September. The northeast monsoon blows from the north-east across India from mid-November to February.
• Influence: Southwest monsoons are seasonal winds driven by the heating differences between land and water. They form when southeasterly trade winds are drawn towards low pressure over northern India and deflected southwest by the Coriolis force. 
• Moisture Content: Southwest monsoons are onshore winds, bringing moisture from the Indian Ocean, resulting in heavy rainfall. Northeast monsoons are offshore winds, blowing from land to sea, and are typically dry.
• Rainfall Contribution: Southwest monsoons account for 75% to 90% of India's annual rainfall, making Mawsynram in Meghalaya the wettest place on Earth. Northeast monsoons contribute some rainfall, especially in the eastern coastal plains of Tamil Nadu, influenced by occasional western disturbances.
• Temperature: Southwest monsoons are warm winds. Northeast monsoons are cold.

Q4. Explain the major factors influencing climate in India.

Ans: The important factors influencing the climate of India include:

• Latitudinal Location: India is located in the Northern Hemisphere, with the Tropic of Cancer (23°30′N) running through its centre. Areas south of this line experience a tropical climate, while those to the north have a sub-tropical climate.
• Altitude and Relief Features: The northern mountainous regions, especially the Himalayas, have an average altitude of up to 6,000 metres. These areas remain cool in summer and receive snowfall in winter. The Himalayas block cold winds from Central Asia, leading to milder winters and concentrating monsoon rains.
• Pressure and Winds: Unique pressure and wind conditions result in a seasonal reversal of wind patterns. The southwest monsoons are vital for rainfall, while upper air circulation and jet streams also play significant roles. Additionally, winter cyclonic disturbances and tropical cyclones during the retreating monsoon season impact the climate.
• Distance from the Sea: Coastal cities like Mumbai, Chennai, and Kolkata enjoy a maritime climate due to the sea's moderating influence. In contrast, inland areas such as Delhi experience more extreme weather due to their distance from the ocean.

Q5. Write briefly about the Arabian Sea branch of the monsoon. (Important)

Ans: The Arabian Sea branch of the monsoon is a key component of the southwest monsoons as they approach the Indian Peninsula. Here are the main points:

• The Arabian Sea branch moves towards the western coast of India from the Arabian Sea, heading southwest.
• When the moisture-laden winds hit the Western Ghats, they cause heavy rainfall on the windward side, making Mumbai much wetter than Pune, which is on the leeward side.
• The Deccan Plateau experiences less rainfall due to its rainshadow effect. 
• In the western and northwestern regions, the Aravalis run parallel to the winds, resulting in less rainfall.
• By the first week of July, areas like western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan start receiving monsoon rains.
• The Arabian Sea branch eventually merges with the Bay of Bengal branch over the northwestern part of the Ganga plains, with Delhi receiving rainfall from either branch.

Q6. Write in brief about the mechanism of the monsoons. (Important) OR What is meant by the term 'monsoon'? Give the main characteristics of monsoons.

Ans: The mechanism of monsoons involves several key factors:

• Differential heating of land and water creates low pressure over land in summer, drawing in moisture-laden winds from the sea.
• The movement of the Inter-Tropical Convergence Zone (ITCZ) shifts northward over the Ganga plain, forming a monsoon trough that attracts winds.
• The northward movement of the westerly jet stream and the presence of the tropical easterly jet stream over the Indian Peninsula bring tropical depressions and cyclones, which are linked to monsoons.
• The Tibetan plateau heats up in summer, creating strong vertical air currents and high pressure at about 9 km above sea level.
• Changes in pressure conditions over the southern oceans, known as the Southern Oscillation, along with the effects of El Niño, also impact monsoon patterns.

Q7. Write a brief account of the conditions and characteristics of the retreating monsoons.

Ans: The months of October and November mark a transition from the hot rainy season to the cool dry winter. During this time:

• The sun moves south, weakening the low-pressure monsoon trough over the Northern Plains, which is replaced by a high-pressure system.The southwest monsoon winds weaken and withdraw from India, particularly from the Northern Plains by early October.

This period, known as the Retreating Monsoon or Transition season, is characterised by:

• Clear skies and rising temperatures. Warm days and cool, pleasant nights. High humidity during the day due to evaporation from the moist land, leading to what is commonly called 'October heat'.

In early November, the low-pressure zone shifts to the Bay of Bengal, resulting in:

• Cyclonic depressions forming over the Andaman Sea, moving towards the Eastern Coast. These tropical cyclones can cause heavy rainfall and significant damage in densely populated areas such as Tamil Nadu, Andhra Pradesh.

Q8. Describe how the Himalayas affect the climate of India.

Ans: The Himalayas significantly influence India's climate by acting as a natural barrier along the northern border. Here are the key effects:

• The mountains, rising to about 6000 metres, block cold winds from Central Asia, leading to milder winters in India.
• They help retain monsoon rains within the Indian subcontinent, ensuring that the eastern and southern regions receive sufficient rainfall.
• As a result, the northern regions experience a different climatic pattern compared to the rest of the country.

Overall, the Himalayas play a crucial role in shaping the climatic conditions and weather patterns across India.

Q9. Give an account of the weather conditions and characteristics of the cold season.

Ans: The cold weather season in India lasts from mid-November to February, with December and January being the coldest months, particularly in the northern regions. This season is characterised by:

• High pressure: A high-pressure area forms in northern India as the sun moves south.
• Northeast trade winds: These winds blow from land to sea, leading to a generally dry season across most of the country.
• Wind patterns: Light winds flow outward from the high-pressure area, mainly from the west and northwest in the Ganga Valley.
• Temperature variations: Days are warm, while nights are cool. Northern temperatures range from 10°C to 15°C, while southern regions, like Chennai, see temperatures between 24°C and 25°C.
• Peninsular region: This area lacks a distinct cold season due to the moderating effect of the sea, although some rainfall occurs on the Tamil Nadu coast from these winds.

Q10. Give a brief account of the hot weather season in India. (Important)

Ans: The hot weather season in India lasts from April to June and has several key features:

• Temperature Variations: In March, temperatures on the Deccan plateau reach about 38°C. In April, temperatures in Madhya Pradesh and Gujarat rise to around 42°C. By May, temperatures can soar to 45°C in northwestern India, while Peninsular India remains cooler due to ocean influences.
• Pressure Changes: Rising temperatures lead to a drop in air pressure, creating a low-pressure area from the Thar Desert to Patna by late May.
• Hot Winds: Strong, dry winds known as 'loo' blow across northern India during the day and may continue into the evening.
• Dust Storms: Common in May, these storms can temporarily lower temperatures and may bring light rain and a cool breeze.
• Thunderstorms: High daytime temperatures can trigger localised thunderstorms by evening, often resulting in heavy rain and winds, referred to as 'Kal Baisakhi' in West Bengal.
• Pre-Monsoon Showers: Towards the end of May, pre-monsoon showers occur, especially in Karnataka and Kerala, aiding the ripening of mangoes.