NCERT Solutions for Class 11th: Ch 4 Climate Indian Physical Environment 


Page No: 55

1. Choose the right answer from the four alternatives given below.

(i) What causes rainfall on the coastal areas of Tamil Nadu in the beginning of winters?
(a) South-West monsoon
(b) Temperate cyclones 
(c) North-Eastern monsoon
(d) Local air circulation
► (c) North-Eastern monsoon

(ii) What is the proportion of area of India which receives annual rainfall less than 75 cm?
(a) Half
(b) One-third 
(c) Two-third
(d) Three-fourth
► (d) Three-fourth

(iii) Which one of the following is not a fact regarding South India?
(a) Diurnal range of temperature is less here.
(b) Annual range of temperature is less here.
(c) Temperatures here are high throughout the year.
(d) Extreme climatic conditions are found here.
► (d) Extreme climatic conditions are found here.

(iv) Which one of the following phenomenon happens when the sun shines vertically over the Tropic of Capricorn in the southern hemisphere?
(a) High pressure develops over North-western India due to low temperatures.
(b) Low pressure develops over North-western India due to high temperatures.
(c) No changes in temperature and pressure occur in north-western India.
(d) ‘Loo’ blows in the North-western India.
► (a) High pressure develops over North-western India due to low temperatures.

(v) In which of the following states in India do we find ‘As’ type of climate as per Koeppen’s classification?
(a) In Kerala and coastal Karnataka
(b) In Andaman and Nicobar Islands
(c) On Coromandel coast
(d) In Assam and Arunachal Pradesh
► (c) On Coromandel coast

Page No: 56

2. Answer the following questions in about 30 words.

(i) What are the three important factors which influence the mechanism of Indian weather?


The three important factors which influence the mechanism of Indian weather are:
• Distribution of air pressure and winds on the surface of the earth.
• Upper air circulation caused by factors controlling global weather and the inflow of different air masses and jet streams.
• Inflow of western cyclones generally known as disturbances during the winterseason and tropical depressions during the south-west monsoon period into India, creating weather conditions favourable to rainfall.

(ii) What is the Inter-Tropical Convergene Zone?


The Inter Tropical Convergence Zone (ITCZ) is a low pressure zone located at the equatorwhere trade winds converge, and so, it is a zone where air tends to ascend.

(iii) What is meant by ‘bursting of monsoon’? Name the place of India which gets the highest rainfall.


The sudden onset of the moisture-laden winds associated with violent thunder and lightening, is often termed as the “break” or “burst” of the monsoons.
Mawsynram in Meghalaya is the place of India which gets the highest rainfall.

(iv) Define ‘climatic region’? What are the bases of Koeppen’s classification?


 A climatic region has a homogeneous climatic condition which is the result of a combination of factors. The bases of Koeppen’s classification are:
• Temperature
• Precipitation

(v) Which type(s) of cyclones cause rainfall in north-western India during winter? Where do they originate?


Western cyclonic disturbances cause rainfall in north-western India during winter. They originate over the Mediterranean Sea.

3. Answer the following questions in not more than 125 words.

(i) Notwithstanding the broad climatic unity, the climate of India has many regional variations. Elaborate this statement giving suitable examples.


Due to the influence of monsoon, India as a whole has broad climatic unity. However, the climate of India has many regional variations expressed in the pattern of winds, temperature and rainfall, rhythm of seasons and the degree of wetness or dryness. There are various examples of this:

• Temperature: In the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh. Churu in Rajasthan may record a temperature of 50°C or more on a June day while the temperature in Tawang (Arunachal Pradesh) is 19°C on the same day.

• Rainfall: Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall
over 1,080 cm in a year while Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period.

• Monsoon: The Ganga delta and the coastal plains of Orissa are hit by strong rain-bearing storms
almost every third or fifth day in July and August while the Coromandal coast, a thousand km to the south, goes generally dry during these months. 

(ii) How many distinct seasons are found in India as per the Indian Meteorological Department? Discuss the weather conditions associated with any one season in detail.


The meteorological department recognise the following four seasons :
(i) the cold weather season
(ii) the hot weather season
(iii) the southwest monsoon season
(iv) the retreating monsoon season.

• The cold weather season: The cold weather season sets in by mid-November in northern India. December and January are the coldest months in the northern plain. The mean daily temperature remains below 21°C over most parts of northern India. The night temperature may be quite low.
The Peninsular region of India, however, does not have any well-defined cold weather season. There is hardly any seasonal change in the distribution pattern of the temperature in coastal areas because of moderating influence of the sea and the proximity to equator.

During the winters, the weather in India is pleasant. The pleasant weather conditions, however, at intervals, get disturbed by shallow cyclonic depressions originating over the east Mediterranean Sea and travelling eastwards.

Winter monsoons do not cause rainfall as they move from land to the sea. It is because they have little humidity and due to anti cyclonic circulation on land. So, most parts of India do not have
rainfall in the winter season. However, there are some exceptions, Rainfall occurs in northwestern India due to western disturbances. Central parts of India and northern parts of southern peninsula also get winter rainfall occasionally.

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