Geography Class 9 : Chapter 4 - Climate

In this page you get NCERT Solution Class 9 Social Science (Geography) Chapter 4 Climate being given. Social Science have four parts. Social Science (Geography) Class 9th has been set by the CBSE Board. The speciality of this page is that here you can download pdf of NCERT Solution Class 9 Social Science (Geography). I expect that the given Class 9 Social Science (Geography) Solution Chapter 4 Climate will be immensely useful to you. 

Chapter 4
Climate

Question Answer

1. What are the controls affecting the climate of India?

Ans. India's climate is affected by latitude, altitude, pressure and winds, distance from the sea, ocean currents and physiography

2. Why does India have a monsoon type of climate?

Ans. India has a monsoon type of climate because it is strongly governed by the monsoon winds. It gets about 90 % of its rainfall due to the monsoons.

 

3. Which part of India does experience the highest diurnal range of temperature and why?

Ans. The diurnal range of temperature means the difference in the temperature of a particular place in a single day. The Thar Desert of Rajasthan in India experiences the highest diurnal range of temperature. This is because, at the Thar Desert the weather condition drastically change from the day to the same night. This creates a great difference between the two.

 

4. Seasonal reversal of wind direction takes place over the Indian subcontinent. Give reasons.

Ans. The pressure and wind conditions over India are unique. During winter, there is a high- pressure area over north of the Himalayas. Cold dry winds blow from this region to the low- pressure area over the oceans to the South. In summer, a low- pressure area develops over interior Asia as well as over northwestern India. This causes a complete reversal of the direction of winds during summer.

 

5. What are Jet streams and how do they affect the climate of India?

Ans. These are winds that blow above 12000 m over the troposphere. These are actually westerly winds blowing at higher altitude. Their speed varies from about 110 km/ h in summer to about 184 km/ h in winter.

The western cyclonic disturbances experience in the north and north - western parts of the country are brought in by subtropical westerly Jet streams. During summer an easterly jet stream called the tropical easterly jet cause heavy rain over peninsular India.

 

6. What is Western Cyclonic Disturbances?

Ans. The Western cyclonic disturbances are weather phenomena of the winter months brought in by the westerly flow from the Mediterranean region. They usually influence in the weather of the north and North Western region of India.

Extra  Questions

 1. Discuss the mechanism of monsoons.

Ans. Mechanism of monsoon:

Mansoon denotes the seasonal reversal in the wind during the year. The term mechanism denotes arrangement or pattern of something duly observed and recorded. India falls in monsoon type of climate owing to its location in south and southeast Asian region. This region is called tropical region between 20°N and 20°S. Half of India in North falls in subtropical and the Southern parts falls in the tropical region.

                  The metrologist found out a fluctuating relationship between the metrological changes going on over the Pacific and the Indian Ocean. Whenever there is a high pressure in the subtropical region of the Pacific Ocean in the northern hemisphere, the pressure in the southern part of Indian Ocean tends to the low and vice - versa. This very fact causes the shifting of wind across the equator in different directions. The difference in pressure at those two places tells the intensity of moisture bearing monsoon winds.

 

2. Which winds account for rainfall along the Malabar Coast?

Ans: Malabar Coast falls in the Arabian Sea. The Arabian Sea branch of monsoon or Western trade winds that do heavy rainfall in Malabar Coast. Collision of rain bearing clouds against elevated landforms of Western Ghats, causes rainfall along the Malabar Coast.

 

3. Why does the rainfall decreases from the east to the west in Northern India?

Ans: This is because monsoon rise from the two sides in the summer season: the Bay of Bengal and Arabian Sea. The Bay of Bengal branch of monsoon causes heavy rainfall in the Brahmaputra valley. Due to the Himalayas, they take a western turn and move up the Ganga valley. But as they move westwards, they become dryer and dryer thereby decreasing rainfall from east to the west. In addition, rainfall also decreases in proportion to the distance from the sea. The Arabian branch of monsoon move parallel to the Aravalli Hills of Rajasthan, so they do not check the monsoons and consequently Rajasthan remains dry.

 

4. Give reasons as to why.

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

Ans: The pressure and wind conditions over India are unique. During winter, there is a high pressure area over North of the Himalayas. Cold dry winds blow from this region to the low pressure area over the ocean to the south. In summer, a low pressure area develops oven interior Asia as well as over northern India. This causes a complete reversal of the direction of winds during summer.

 

(ii). The bulk of rainfall in India is concentrated over a few months.

During the four months, i.e., June to September, South-west monsoon blow northwards in two branches: Arabian Sea branch and Bay of Bengal branch.
             Both of these branches of monsoon do rain in Indian peninsula low pressure is existed. However, the withdrawal of the monsoon begins in the western part of the North -Western states of India by early September. Rain is concentrated for four months only because of Inter Tropical Convergence Zone and ENSO phenomenon.

 

(iii). The Tamil Nadu coast receives winter rainfall.

Ans: North East monsoon starts blowing in October month from the land i. e. , North Eastern parts of India to the sea. These bear no water till their asses at the Bay of Bengal. However, they get some moisture from the sea here and cause rain in the coast of Tamil Nadu.

 

(iv). The Delta region of the Eastern Coast is frequently struck by cyclones.

Ans: Low pressure conditions are formed during October and November every year on the Bay of Bengal. Owing to this shift transfer of pressure, cyclonic depression is formed in the Andaman sea. These are called tropical cyclones and spread devastation in eastern deltas.

 

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

 Ans: This happens due to collision of rain bearing Arabian Sea branch of monsoon winds against the high elevated Western Ghats and depletion of water there. Again, the Aravalli Hills being not much elevated, the monsoon winds pass from there untrained.

 

5. Define monsoons. What do you understand by 'break' in monsoon?

Ans: Monsoons are generally rain bearing and directing winds. This term has been derived from the Arabic word "mausim", first used by the Arab traders who used to come India for trading through sea routes. It means season. Monsoon refers to the seasonal reversal of the wind system in the wind direction during a year.

Break in monsoon: Rains taking place only for a few days at a time is called 'break in monsoon'. It is related to to the movement of the monsoon trough.

 

6. Why is the monsoon considered a unifying bond?

Ans: The monsoon is considered as a unifying bond for this subcontinent.

• The Himalayas protect the subcontinent from extremely cold winds from Central Asia.

• The peninsular plateau, under the influence of the sea from three sides, has moderate temperature.

• The unifying influence of the monsoon on the Indian subcontinent is quite perceptible.

• The seasonal alternation of the wind system and the associated weather conditions provide a rhythmic cycle of seasons.

• The Indian landscape, animal and plant life, its entire agricultural calendar and the life of the people, including their festivals, revolves around this phenomenon.

• This monsoon winds bind the whole country by providing water to set the agricultural activities in motion.

 

7. Describe the regional variations in the climatic conditions of India with the help of suitable examples.

Ans: The climate of India is described as the 'monsoon' type. Despite an overall unity in the general pattern, there are perceptible regional variations in climatic conditions within the country.

a) In summer the temperature is about 50°C in some parts of Rajasthan desert whereas it may be around 20°C in Pahlgam in Jammu and Kashmir.

b) While precipitation is mostly in the form of snowfall in the upper part of Himalayas, it rains over the rest of the country.

c) The annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and western Rajasthan.

d) Most parts of the country receive rainfall from June to September, but the Tamil Nadu coast gets most of its rain during October and November.

 

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

Ans: 

• The temperature gradually decreases during this period from South to the north.
• Days are experienced warm while the nights are called.
• Days are short while nights are longer.
• Most part of the country remains almost dry during this period and only Tamil Nadu coast receives heavy winter rains.
• Coastal area enjoys moderate temperature throughout the year.

 

9. Give the characteristics and effect of the monsoon rainfall in India.

Ans. The monsoon

a) It gives water in glut to the entire territories of India except some leeward sides, rain Shadow region and Thar like deserts.

b) Early in the season, the windward side of the Western Ghats receives heavy rainfall (more than 250 cm).

c) The rain shadow areas of Deccan plateau and parts of Madhya Pradesh also receive scanty rains.

d) The maximum rainfall is recorded in the north-eastern part of the country.

e) Indian monsoon take 'breaks' viz. interspersed with rainless intervals.

 

10. Rearrange the following stations in two different sequences: a) Bangaluru, b)Mumbai, c)Kolkata, d) Jodhpur, e)Chennai f)Nagpur g)Shillong h)Thiruvananthapuram i)Leh j) Delhi.

A. According to their distance from the equator.

Ans: a) Thiruvananthapuram- ( 8°29'N)   b) Bangaluru- (12°58'N)   c) Chennai. (13°6' N)   d) Mumbai. (19°N)   e) Nagapur. (12°9'N)   f) Kolkata. (22°34'N)   g) Shillong. (25°36'N)   h) Jodhpur. (26°18'N)   i) Delhi. (29°N)   j) Leh. (34°N)

B. According to their altitude above mean sea- level.

Ans: 1) Kolkata   2)Chennai   3)Mumbai   4)Thiruvananthapuram   5)Delhi   6)Jodhpur   7)Nagpur   8)Bengaluru   9)Shillong   10)Leh.

 

11.a) Name two rainiest stations.

Ans: Shillong and Mumbai.

 

b) Name two driest stations.

Ans: Let and Jodhpur.

 

c) Two stations with most equable climate.

Ans: Mumbai and Bengaluru

 

d) Two stations with the most extreme climate.

Ans: Delhi and Jodhpur.

 

e) Two stations most influenced by the Arabian branch of Southwest monsoon.

Ans: Mumbai and Goa.

 

f) Two stations most influenced by the Bay of Bengal branch of Southwest monsoon.

Ans: Meghalaya and Mizoram.

 

g) Two stations influenced by both branches of the Southwest medicines.

Ans: Kerala and Tamil Nadu.

 

h) Two stations influenced by retreating and northeast monsoons.

Ans: Coastal regions of Tamil Nadu and Andhra Pradesh.

 

i) Two stations receiving winter showers from the western disturbances.

Ans: Western Uttar Pradesh and Punjab.

 

j) the two hottest stations in the month of:-

• February. - Chennai and Thiruvananthapuram.

• April - Chennai and Nagpur.

• May - Nagpur and Delhi

• June - Jodhpur and Delhi.

 

12. Why are Thiruvananthapuram and Shillong rainier in June than in July?

Ans: Thiruvananthapuram is located in the southernmost part of India. By June 1 , monsoon enters India from the south. One of the branch of monsoon winds i.e., Bay of Bengal branch which are moisture laden hits the hill located around Shillong and showers heavy rainfall. Thiruvananthapuram and Shillong are the first in the way of monsoon winds, they are more rainier in June than in July.

 

13. Why is July rainier in Mumbai than in Thiruvananthapuram.

Ans: In Mumbai, the monsoon winds rising from Arabian Sea continuously pour rainfall due to the presence of Western Ghats.

 

14. Why are Southwest monsoon less rainy in Chennai?

Ans: For Southwest monsoon, Chennai lies in rainshadow region.

 

15. Why is Shillong rainier than Kolkata?

Ans: In Shillong Garo, Kashi and jayntia Hills trap the monsoon winds and force them to shed rainfall. But in Kolkata, the monsoon winds reach comparatively late and there is no such Hills located in Bengal which could trap the monsoon winds.

 

16. Why is Kolkata rainier in July than in June unlike Shillong which is rainier in June than in July?

Ans: Kolkata is rainier in July thanJune because monsoon winds reach there in July. But monsoon winds which are moisture-laden reach first in Shillong and pour heavy rainfall in the month of June.

 

17. Why does Delhi receive more rain than Jodhpur.

Ans: Jodhpur lies to the west of Delhi. It means the monsoon winds first reach at Delhi, then at Jodhpur where they become almost dry. Delhi receives rainfall from monsoon winds as well as Western disturbances whereus Jodhpur receive rain full only from monsoon winds.

 

18. NOW THINK WHY

a) Thiruvananthapuram has equable climate?

Ans: Equable climate is generally experienced in all stations falling nearer to the sea as the moisture does not allow high pressure to be formed anytime here. This fact also applies on Thiruvananthapuram and we see here equable climate throughout the year.

 

b) Chennai has more rains only after the fury of monsoon is over in most part of the country?

Ans: Monsoon winds start retreating in September to October months. This or replaced by either Northwest trade winds i.e., winds blowing from extreme North West of India. These winds receive vapour while moving over the Bay of Bengal to which they immediately carry to the Coromandel Coast in Tamil Nadu. These rain bearing winds collide against Eastern Ghats and thus, Coramandal Coast including Chennai receives heavy rainfall during winter season.

 

c) Jodhpur has a hot desert type of climate?

Ans: Jodhpur falls in the rain Shadow region and it is situated proxy to the Thar Desert. This station has therefore, extreme climate. Hot winds namely Loo starts blowing here during summer that makes it dusty.

 

d) Leh has moderate precipitation almost throughout the year?

Ans: Northeast trade winds blow throughout the year in Leh district of Jammu and Kashmir. Monsoon winds never reach up to this altitude as they get lost their water completely. This station receives mostly snowfall because of its super altitude. Being in the coldest place, water drops are freeze here. Thus we can see here only scanty precipitation

 

(e) While in Delhi and Jodhpur most of the rain is confined to nearly three months, in Thiruvanantapuram and Shillong it is almost nine months of the year?

Ans. Monsoon winds always prefer to blow over Thiruvanantpuram and Shillong irrespective of, their distance from the sea. The wind blowing from Indian Ocean, Bay of Bengal and the Arabian Sea simultaneously cover these stations during rainy season. Disturbances are caused over Andaman Sea and the Bay of Bengal as a result of the north-east trade winds usually fill the void created by the retreating monsoon during winter season. These winds while passing over above said sea; generally get vapour and do heavy rain in Shillong and Thiruvanantpuram. Thiruvanantpuram falls adjacent to the Arabian Seas and Indian Ocean and Shillong is also nearer to Bay of Bengal and Andaman Sea. Delhi and Jodhpur are at larger distance from the sea coupled with nearer to the terrestrial region as they also fall in subtropical belt. Hence, both these stations receive heavy rain during three months while these remain dry during the next nine months of the year. We can state in brief that quantum of win here is affected due to different landforms, temperature, distance from the sea and mean altitude from the sea-level.