NCERT Solutions for Class 11 Geography Chapter 4 - Climate

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77. 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

(d) Local air circulation

Ans. (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

(d) Three-fourth

Ans. (b) One-third

(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.

(d) Extreme climatic conditions are found here.

Ans. (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.

(d) ‘Loo’ blows in the north-western India.

Ans. (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

(d) In Assam and Arunachal Pradesh

Ans. (c) On Coromandel coast

78. Answer the following questions in about 30 words.

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

Ans. The three important factors which affect the mechanism of Indian weather are:

(a) Air pressure and wind patterns across the earth’s surface.

(b) Upper air circulation which is caused by factors controlling global weather and the inflow of different air masses and jet streams.

(c) Indian meteorological conditions are favourable for rainfall due to the inflow of western cyclones, also known as disturbances, during the winter and tropical depressions during the southwest monsoon season.

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

Ans. The Inter Tropical Convergence Zone (ITCZ) is a low-pressure zone located at the equator where trade winds converge, and so, it is a zone where air tends to ascend. The ITCZ is positioned between latitudes 20° and 25° north in July (over the Gangetic plain). These are occasionally referred to as the monsoon trough. The formation of a thermal low across north and northwest India is encouraged by this monsoon trough. The southern hemisphere’s trade winds begin to blow from the southwest to the northeast due to the Coriolis force as a result of the ITCZ’s shift, which occurs between 40° and 60°E longitudes. Southwest monsoon develops.

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

Ans. Sudden precipitation is brought on by strong winds and intense lightning. It is referred to as the monsoon bursting. Only when the western jet stream has left the area about 15°N latitude does the easterly jet stream begin to develop. The burst of the Indian monsoon is attributed to this easterly jet stream. The northeast and the hills of Meghalaya experience the most rainfall, along with the west coast, the Western Ghats, and the sub-Himalayan regions.

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

Ans. A climatic region has a homogeneous climatic condition resulting from a combination of factors. In all climatic categorization schemes, two key factors that are regarded as decisive are temperature and rainfall. Koeppen found a strong correlation between climate and vegetation distribution. In order to categorise the climates, he chose specific temperature and precipitation values, connected them to plant distribution, and utilised those values. For the purpose of identifying climatic groupings and kinds, Koeppen suggested the use of capital and small letters. Four of the primary climatic groupings that Koeppen identified are based on temperature, while one is based on precipitation.

(a) Tropical climates,

(b) Dry climates,

(d) Cool temperate climates,

(e) Polar/Ice climates.

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

Ans. In winters, a western cyclonic disturbance brings rain to northwestern India. The westerly jet stream carries the western cyclonic disturbances into India during the winters from the west and northwest. These disturbances originate over the Mediterranean Sea. An increase in the average nighttime temperature generally signals an impending approach to these cyclone disturbances.

79. 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.

Ans. The monsoon season highlights India’s bond with the rest of south-east Asia. Although the monsoon climate is generally viewed as uniform, regional variations that distinguish the weather and climate of various parts of India should not be ignored. All of these places share a monsoon climate, despite the fact that the climates of Kerala and Tamil Nadu in the south and climate of Uttar Pradesh and Bihar in the north are very distinct from one another.

(a) While the temperature occasionally reaches 55°C in western Rajasthan in the summer, it could go as cold as minus 45°C in the wintertime near Leh. On a June day, Churu in Rajasthan may have temperatures of 50°C or more, whereas in Tawang it may barely reach 19°C.

(b) In Dras (Jammu and Kashmir), the temperature on a December night may drop down to minus 45°C, whereas Thiruvananthapuram or Chennai may
record 20°C or 22°C on the same night.

(c) The change in temperature between day and night can be as little as seven or eight degrees Celsius in Kerala and the Andaman Islands. However, in the Thar desert, where daytime temperatures may reach 50°C, nighttime lows of 15°–20°C may also be experienced.

(d) While the Coromandal coast, a thousand kilometres to the south, often has dry weather in July and August, the Ganga delta and the coastal plains of Odisha are frequently struck by powerful storms that bring heavy rain. Most of the nation has rain from June to September. However, Tamil Nadu’s coastal regions experience rain during the start of the winter season.

These examples confirm seasonal variations in temperature from place to place and region to region in India. Despite these differences and variations, the climate of India is monsoonal in rhythm and character.

(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.

Ans. In India, as per the Indian Meteorological Department, there are four distinct seasons:

(a) Winter Season (from December to February)

(b) Summer Season (from March to May)

(d) Retreating Monsoon (from October to November).

Summer Season: In north India, the summer months are April, May, and June.

Most of India’s reported temperatures to fall between 30° and 32°C. The Deccan Plateau experiences the greatest daytime temperature of around 38°C in March, while Gujarat and Madhya Pradesh experience temperatures between 38°C and 43°C in April. As the heat belt travels farther north in May, temperatures around 48°C are not unusual in India’s northwest.

In comparison to north India, the hot weather season in south India is moderate and not as severe. The peninsular topography of south India and the seas’ moderating influence keep the temperature there lower than it is in north India. As a result, the temperature ranges between 26 and 32 degrees. The Western Ghats hills never experience temperatures beyond 25°C because of their altitude. In coastal areas, the temperature rises from the shore to the interior parts, rather than falling from north to south. In the summer, the average daily minimum temperature stays over 26°C and is still relatively high.