Solutions, questions, answers, and notes of chapter 6: Climate which is a part of social science class 9 syllabus of students studying under the Nagaland Board of School Education. However, these notes should be used only for references and additions/modifications should be made as per the requirements.
Introduction
Climate is the typical weather conditions of an area over a long period of more than thirty to thirty-five years. The climate of a place influences its flora (plants) and fauna (animals). It accounts for environmental diversity. It patterns the livelihood of the people.
Climate is the long-term effect of the Sun’s radiation on the rotating Earth’s surface and atmosphere. It can be understood most easily in terms of annual or seasonal averages of temperature and precipitation. Because of the unusual topography and geographical position of India, climatic conditions are widely diversified, both on a regional as well as a seasonal basis. This diversity is in the range of extremes – from tropical to temperate zones. The temperature extremes are confined largely to the slopes of the Himalayas. Except in the more mountainous regions, the rest of India has a uniformly tropical climate. Seasonal variations, resulting from the southwestern and northeastern monsoons profoundly influence temperature, humidity and precipitation throughout the subcontinent.
The climate of a country is mainly based on the range of its temperature, rainfall, atmospheric pressure and direction of winds.
Textual questions and answers
Choose the correct answer
1. The direction of the monsoon wind in summer is:
(a) South-west (b) North-west (c) North-east (d) South-east
Answer: A. South-west
2. What primarily causes a decrease in air temperature from the equator towards the poles?
(a) Altitude (b) Ocean currents (c) Latitude (d) Distance from the sea
Answer: C. Latitude
3. The period of transition from hot and rainy to dry and cold season occurs in:
(a) August-September (b) September-October (c) October-November (d) November-December
Answer: C. October-November
4. The monsoons begin to withdraw from the Northern Plains in the month of:
(a) August (b) September (c) October (d) November
Answer: C. October
5. Identify the correct option that describes the season given below:
I. This season is marked by dry weather and excessive heat
II. The Sun shines vertically over the Tropic of cancer
III. Thunderstorms accompanied by dusty winds are common
Options: (a) Cold weather season (b) Hot weather season (c) Advancing Monsoon (d) Retreating Monsoon
Answer: B. Hot weather season
Very Short Answer Type Questions.
1. Define climate.
Answer: Climate is the typical weather conditions of an area over a long period of more than thirty to thirty-five years. The climate of a place influences its flora (plants) and fauna (animals).
2. List the elements that affect the climate of India.
Answer: The important elements that affect the climate of India are temperature and precipitation.
3. List the factors that determine the climate of a place.
Answer: The factors that determine the climate of a place are:
(i) Relief and Location
(ii) Altitude
(iii) Distance from the Sea
(iv) Pressure and Winds
(v) Upper-Air Circulation
4. List the four main seasons of India.
Answer: The four main seasons of India are:
(i) Hot Weather Season
(ii) Cold Weather Season
(iii) Advancing Monsoon Season
(iv) Retreating Monsoon Season
5. List the two branches of advancing monsoon.
Answer: The two branches of advancing monsoon are:
(i) The Arabian Sea Branch
(ii) The Bay of Bengal Branch.
Short answer type questions
1. How do the Himalayas affect the climate of India?
Answer: The great Himalayan range separates the Indian subcontinent from the rest of Asia, thus preventing the bitterly cold winds from Central Asia from entering the country.
2. Give two characteristics of the winter season.
Answer: Two characteristics of the winter season are:
i. Northeast monsoon takes over from the southwest monsoon.
ii. Temperature goes on decreasing towards the north of Tropic of Cancer.
4. How have monsoons been a ‘unifying bond’ in India?
Answer: The Himalayas are protective barriers that stop the cold winds from entering the subcontinent. This allows even the areas of northern India which lie on the same latitude to experience uniform high temperatures.
Long answer type questions
1. Write about the characteristic features of hot weather season and cold weather season in India.
Answer: The characteristic features of the hot weather season are:
i. This season is marked by dry weather and excessive heat.
ii. The sun shines vertically over the Tropic of cancer.
iii. The whole of tropical India, south of the Himalayas, experiences very high temperatures.
The characteristic features of the cold weather season are:
i. Northeast monsoon takes over from the southwest monsoon.
ii. Light winter rainfall in northwest India is very useful for the rabi crop, especially wheat.
iii. Temperature goes on decreasing towards the north of Tropic of Cancer.
2. How do south-westerly winds bring rains in India?
Answer: In late summer, the low-pressure condition over the Northern Plains intensifies. This attracts the trade winds of the Southern Hemisphere. The South-East Trade winds originate over warm sub-tropical areas of the southern oceans, cross the equator and blow in a south-westerly direction to India. They are moisture-laden and bring rainfall to India as South-West monsoon.
3. Discuss features of the ‘Retreating Monsoons’.
Answer: The monsoon trough of low pressure grows weaker by October-November. It is then slowly replaced by high pressure. The monsoon’s outreach is rendered unsustainable and the gradual withdrawal begins. This is known as the ‘retreat of monsoon. By the time October begins the monsoons withdraw from the Northern Plains.
The period of transition from hot and rainy to dry and cold season occurs in the months of October-November. Clear skies and rising temperatures are prominent marks of the retreating monsoon. During the daytime, the temperature remains high but nights are pleasant and cool
4. Discuss the monsoon season in India.
Answer: The monsoon as a unifying bond is an obvious fact. The seasonal alternation of the wind systems and the associated weather conditions provides a rhythmic cycle of the season. The uncertainties of rain and the uneven distribution are prominent characteristics of the monsoons. It is evident from the fact that sometimes parts of the country may be facing the fury of floods due to heavy rains, while other parts may be reeling under severe drought conditions due to scanty rainfall. The most important aspect of Indian rainfall is that it is largely controlled by orography.
5. Explain how upper air circulation operates as a factor influencing the climate of India.
Answer: The higher level of the atmosphere experiences an altogether different pattern of air circulation. These fast-blowing winds are called jet streams. The westerly jet stream gets divided into two streams after it meets a barrier in the Tibetan Highlands. The southern branch blows in an eastward direction in the Himalayas. It has a great influence on the winter in India. During summer, the westerly jet stream moves northwards. Later on, an easterly jet stream takes its place to flow over northern India. Tropical depressions are brought into India by an easterly jet stream and low-pressure area over land. These depressions aid in the distribution of monsoon rainfall over the whole of India.
6. Why is the western part of Rajasthan arid in spite of the Aravalli Hills? [HOTS]
Answer: The western part of Rajasthan is arid in spite of the Aravali Hills because of the following reasons.
(i) The Aravallis system is unable to prevent the south-western summer monsoon winds, and hence, western Rajasthan remains practically dry, while the southern parts do get some rainfall.
(ii) This western part lies at a great distance from the Bay of Bengal, and therefore, the Bay of Bengal monsoon becomes dry and loses most of its moisture by the time it reaches Rajasthan.
(iii) This area is also far away from the Himalayan region, and therefore, it does not come under the influence of monsoons.
7. Why does Shillong has more rainfall than Kolkata? [HOTS]
Answer: Shillong is stationed at a higher altitude compared to Kolkata, and thus, due to the presence of the hills, the Bay of Bengal branch of the southwest monsoon gets obstructed. This results in a heavy shower in Shillong. Kolkata, which is situated to the west of Shillong, receives less rainfall because the rainfall decreases from east to west in North India.
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