NCERT Solutions For Class 9 Geography Social Science Chapter 4: Climate
1. Choose the correct answer from the four alternatives given below.
(i) Which one of the following places receives the highest rainfall in the world?
(a) Silchar
(b) Mawsynram
(c) Cherrapunji
(d) Guwahati
Answer : (b) Mawsynram
(ii) The wind blowing in the northern plains in summers is known as:
(a) Kaal Baisakhi
(b) Loo
(c) Trade Winds
(d) None of the above
Answer : (b) Loo
(iii) Which one of the following causes rainfall during winters in north-western part of India.
(a) Cyclonic depression
(b) Retreating monsoon
(c) Western disturbances
(d) Southwest monsoon
Answer : (a) Cyclonic depression
(iv) Monsoon arrives in India approximately in:
(a) Early May
(b) Early July
(c) Early June
(d) Early August
Answer : (c) Early June
(v) Which one of the following characterises the cold weather season in India?
(a) Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights
Answer : (c) Cool days and cold nights
2. Answer the following questions briefly.
(i) What are the controls affecting the climate of India?
Answer: There are six major controls of the climate of any place. They are:
1. Latitude
2. Altitude
3. Pressure and wind system
4. Distance from the sea
5. Ocean currents and
6. Relief features
(ii) Why does India have a monsoon type of climate?
Answer: Jet Stream, Coriolis Force, Inter Tropical Convergence Zone (ITCZ), El Nino are some of the reasons why India has a monsoon type of climate.
(iii) Which part of India does experience the highest diurnal range of temperature and why?
Answer: Diurnal range --- Diurnal range is the difference between day and night temperatures .
Part of India that experiences the highest diurnal range of temperature is Thar Desert. This is present towards western side of India in the state of Rajasthan.
This is because it is filled with sand which gets heated up quickly during day and cooled up very quickly during nights. There is no sea closer to this area and hence there is no moderating effect.
(iv) Which winds account for rainfall along the Malabar coast?
Answer: South-West Monsoon Winds.
(v) What are Jet streams and how do they affect the climate of India?
Answer: These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere. Their speed varies from about 110 km/h in summer to about 184 km/h in winter.
The westerly jet streams are responsible for bringing western cyclonic disturbances to north west India resulting in rainfall in winters.
(vi) Define monsoons. What do you understand by “break” in monsoon?
Answer: The word monsoon is derived from the Arabic word ‘mausim’ which literally means season. ‘Monsoon’ refers to the seasonal reversal in the wind direction during a year.
The monsoon rains take place only for a few days at a time. They are interspersed with rainless intervals. These are known as “break” in monsoon.
(vii) Why is the monsoon considered a unifying bond?
Answer:
➡️ The Indian landscape, its animal and plant life, its entire agricultural calendar and the life of the people, including their festivities, revolve around this phenomenon.
➡️ Year after year, people of India from north to south and from east to west, eagerly await the arrival of the monsoon.
➡️ These monsoon winds bind the whole country by providing water to set the agricultural activities in motion.
➡️The river valleys which carry this water also unite as a single river valley unit.
3. Why does the rainfall decrease from the east to the west in Northern India?
Answer: It is because the wind loses the moisture content.
4. Give reasons as to why.
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent?
Answer: Seasonal change in wind direction due to pressure difference.
(ii) The bulk of rainfall in India is concentrated over a few months.
Answer: Rainfall is dependent on the South West Monsoon winds, it rapidly progresses and covers large swathes of the country by July.
(iii) The Tamil Nadu coast receives winter rainfall.
Answer: It is because of North-East monsoon winds.
(iv) The delta region of the eastern coast is frequently struck by cyclones.
Answer: The Bay of Bengal faces frequent pressure changes.
(v) Parts of Rajasthan, Gujarat the leeward side of the Western Ghats are drought-prone.
Answer: Because they fall in the rain shadow region of Aravali Mountains.
5.Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Answer: India shows wide variations in climatic conditions across various regions.
➡️ For example; during winter season, the temperature goes into negative in the Himalayan region. In the northwestern India, temperatures can range between zero degree to 15°C during winter. During the same season, the temperature in Chennai remains a comfortable 25°C.
➡️ The same variation can be seen in summer as well, while the temperature in Rajasthan can hover around 47°C, it is a comfortable 30°C in Chennai.
6. Discuss the mechanisms of the monsoon.
Answer:
➡️ Due to Sun, there is differential heating of land and water.
➡️ ITCZ shifts over Ganga plains during the summer.
➡️ The high-pressure area, east of Madagascar affects the monsoon.
➡️Due to strong vertical air currents and formation of high pressure over Tibetan plateau, the plateau gets intensely heated during the summer.
Due to above mentioned factors south east wind moves toward India as south west momsoon.
7. Give an account of weather conditions and characteristics of the cold season.
➡️ Cold weather season is also called as winter.
➡️ It starts in the month of November and ends in February. December and January are the coldest months.
➡️ This season is characterized by warm days and cold nights.
➡️ Temperature decreases from south to north.
➡️ In southern India, the average winter temperatures range from 24-25 degree centigrade and in northern parts of the country temperature remains about 10-15 degree centigrade.
8. Give the characteristics and effects of the monsoon rainfall in India.
(i) The duration of the monsoon is between 100 to 120 days from early June to mid-September.
(ii) Around the time of its arrival, the normal rainfall increases suddenly and continues for several days. This is known as the ‘burst’ of the monsoon.
(iii) The monsoon has characteristic wet and dry spells or ‘breaks’ in rainfall. The monsoon rains take place only for a few days at a time. They are interspersed with rainless intervals.
(iv) The moisture is carried by pulsating south westerlies that are affected by different atmospheric conditions, thereby giving monsoon rains an uncertain character. The annual rainfall is highly variable from year to year
(v) The rainfall is unevenly distributed across the Indian landscape. Parts of the western coast and north-eastern India receive the maximum rainfall. Regions such as parts of Rajasthan, Gujarat, Leh and the leeward side of the Western Ghats receive very little rainfall.
Effects of monsoon rainfall in India:
(a) Indian agriculture is largely dependent upon the water from the monsoon rains. Late, low or excessive rains have a negative impact upon crops.
(b) Due to the uneven distribution of rainfall across the country, there are some regions that are drought prone and some that are flood afflicted.
(c) The monsoon provides India with a distinct climatic pattern. Hence, in spite of the presence of great regional variations, it has a unifying influence upon the country and its people.
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