NCERT Solutions for Class 9 Social Science Geography Chapter 4 Climate

NCERT Solutions for Class 9 Geography Chapter 4 Climate contains answers to the exercise questions given in ‘Contemporary India’. These solutions will help students for the preparation of CBSE Class 9 SST exam. All the answers are useful for exams as most of the questions are asked from the NCERT textbooks. So, students can study these solutions and score high in their exams.

NCERT Solutions For Class 9 Geography Chapter 4: Climate PDF

Question 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

Question 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: latitude, altitude, pressure and wind system, distance from the sea (continentality), ocean currents and relief features

(ii) Why does India have a monsoon type of climate?

Answer: India comes in the Inter-Tropical Convergence Zone (ITCZ) also with various other factors, like the El Nino, Jet Stream and Coriolois Force are the reasons for monsoon type of climate in India.

(iii) Which part of India does experience the highest diurnal range of temperature and why?

Answer: Northwestern part of India experiences the highest diurnal range of temperature. This happens because of the presence of the Thar Desert and also because this region does not have the moderating influence of the ocean.

(iv) Which winds account for rainfall along the Malabar coast?

Answer: Malabar Coast gets rains from depressions and cyclones.

(v) What are Jet streams and how do they affect the climate of India?

Answer: Jet Streams 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. A number of separate jet streams have been identified. The most constant is the mid-latitude and subtropical jet stream. They cause depressions during the monsoon season.

(vi) Define monsoons. What do you understand by “break” in monsoon?

Answer: Breaks in monsoon are related to the movement of the monsoon trough. For various reasons, the trough and its axis keep on moving northward or southward, which determines the spatial distribution of rainfall. When the axis of the monsoon trough lies over the plains, rainfall is good in these parts. On the other hand, whenever the axis shifts closer to the Himalayas, there are longer dry spells in the plains and widespread rain occurs in the mountainous catchment areas of the Himalayan rivers.

(vii) Why is the monsoon considered a unifying bond?

Answer: Although there are wide variations in weather patterns across India, the monsoon brings some unifying influences on India. The Indian landscape, its flora and fauna, etc. are highly influenced by the monsoon. The entire agricultural calendar in India is governed by the monsoon. Most of the festivals in India are related to the agricultural cycle. These festivals may be known by different names in different parts of the country, but their celebration is decided by the monsoon.

Question 3: Why does the rainfall decrease from the east to the west in Northern India.

Answer: The Bay of Bengal branch of the monsoon winds moves towards the northeast and return westwards covering the northern plains. While they move towards the west, their moisture contains tends to reduce with subsequent rains. Hence the rainfall decreases from east to west in northern India.

Question 4: Give reasons as to why.

(i) Seasonal reversal of wind direction takes place over the Indian subcontinent?

Answer: Seasonal reversal of wind direction over the Indian subcontinent takes place due to pressure differential. El Nino has major role to play in the seasonal reversal of wind direction over the Indian subcontinent.

(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: The Tami Nadu coast receives winter rainfall because of movement of low-pressure conditions to the Bay of Bengal.

(iv) The delta region of the eastern coast is frequently struck by cyclones.

Answer: The Bay of Bengal is the centre of various pressure changes and hence there is always a chance of development of cyclone. Due to this, the delta region of the eastern coast is frequently struck by cyclones.

(v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.

Answer: The parts fall in the rain shadow area of the Aravalli. Hence, they are drought prone and don’t receive much of rainfall.

Question 5: Describe the regional variations in the climatic conditions of India with the help of suitable examples.

Answer: The cold weather season begins from mid-November in northern India and stays till February. December and January are the coldest months in the northern part of India. The temperature decreases from south to north. The average temperature of Chennai, on the eastern coast, is between 24° – 25° Celsius, while in the northern plains, it ranges between 10°C and 15° Celsius. Days are warm and nights are cold. Frost is common in the north and the higher slopes of the Himalayas experience snowfall

In March, the highest temperature is about 38° Celsius, recorded on the Deccan plateau. In April, temperatures in Gujarat and Madhya Pradesh are around 42° Celsius. In May, the temperature of 45° Celsius is common in the northwestern parts of the country. In peninsular India, temperatures remain lower due to the moderating influence of the oceans.

Question 6: Discuss the mechanism of monsoons.

Answer: Following are the factors responsible for the mechanism of monsoon:

  • The Sun causes differential heating and cooling of land and water. This creates low pressure on the landmass of India and high pressure over the ocean surface.
  • The Inter Tropical Convergence Zone (ITCZ) is normally positioned about 5°N of the equator. It shifts over the Ganga plains during summer. It is also known as the monsoon trough during the monsoon season.
  • The high pressure area, east of Madagascar is approximately 20°S over the Indian Ocean. This area affects the Indian Monsoon.
  • The Tibetan plateau gets intensely heated during summer. This results in strong vertical air currents and formation of high pressure over the plateau. This high pressure zone is about 9 km above the sea level.
  • The westerly jet stream move to the north of the Himalayas, and the tropical easterly jet stream moves over the Indian Peninsula during summer.
  • The periodic change in pressure conditions between Pacific Ocean and the Indian Ocean that is known as the Southern Oscillation or SO also affects the monsoon.
  • The difference in pressure over Tahiti and Darwin is computed to predict the intensity of the monsoons. Tahiti (18°S/149°W) lies in the Pacific Ocean and Darwin (12°30’S/131°E) lies in northern Australia. If the pressure differences are negative, it means a below average and late monsoon.

Question 7: Give an account of weather conditions and characteristics of the cold season.

Answer: The cold weather season begins from mid-November in northern India and stays till February. December and January are the coldest months in the northern part of India. The temperature decreases as we go from the south to the north. The average temperature in Chennai, on the eastern coast, is between 24° – 25° Celsius. Whereas in the northern plains, it ranges between 10°C and 15° Celsius. Here, the days are warm and nights are cold. Frost is common in the north and the higher slopes of the Himalayas experience snowfall. During this season, the northeast trade winds prevail over the country. They blow from land to sea and hence, for the most part of the country, it is a dry season.

Some amount of rainfall occurs on the Tamil Nadu coast from these winds as here they blow from sea to land. In the northern part of the country, a feeble high-pressure region develops, with light winds moving outwards from this area. Influenced by the relief, these winds blow through the Ganga valley from the west and the northwest. The weather is normally marked by clear sky, low temperatures and low humidity and feeble, variable winds.

A characteristic feature of the cold weather season over the northern plains is the inflow of cyclonic disturbances from the west and the northwest. These low-pressure systems originate over the Mediterranean Sea and western Asia and move into India, along with the westerly flow. They cause the much-needed winter rains over the plains and snowfall in the mountains. Although the total amount of winter rainfall (locally known as ‘Mahawat’) is small, they are of immense importance for the cultivation of ‘rabi’ crops. The peninsular region does not have a well-defined cold season. There is hardly any noticeable seasonal change in temperature pattern during winters due to the moderating influence of the sea.

Question 8: Give the characteristics and effects of the monsoon rainfall in India.

Answer: Characteristics of the monsoon rainfall in India:

  • The duration of the monsoon varies from 100 to 120 days from early June to mid- September.
  • Around the time of its arrival, the normal rainfall increases suddenly and
  • continues regularly for several days. This is called the ‘burst’ of the monsoon.
  • They are distinguished from the pre-monsoon showers because of their increase in rainfall amount and regularity.
  • The monsoon arrives at the southern tip of the Indian Peninsular generally by the first week of June.
  • The rainfall is unevenly distributed across the country.

Effects of the monsoon rainfall in India:

  • Agriculture in India largely depends on Indian monsoons for water. Late, Low or excessive rains have a negative impact on crops.
  • Due to uneven distribution of rainfall across the country, there are few places that are drought-prone and few are flood affected.
  • The monsoon provides India with a diverse 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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