NCERT Solutions - Climate

Q1: 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
Ans: (c)
Explanation: At the beginning of winter (October-December) the winds reverse and north-easterly winds blow from the land towards the Bay of Bengal and then pick up moisture. These north-easterly or retreating monsoon winds bring rainfall to the Coromandel Coast and coastal Tamil Nadu.

(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
Ans: (d) Three-fourth
Explanation: Nearly three-fourths of India's total area receives less than 75 cm of rainfall annually. Large parts of north-western, central and western India receive relatively low rainfall, while heavy precipitation is confined to specific regions such as the north-east and the western Ghats.

(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.
Ans: (d)
Explanation: South India, being closer to the equator and surrounded by the sea, has smaller diurnal and annual temperature ranges and relatively high temperatures throughout the year. Extreme climatic conditions are not common there, so option (d) is not a correct fact about South India.

(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.
Ans: (a)
Explanation: When the sun is vertically over the Tropic of Capricorn (southern hemisphere summer), the northern hemisphere, including north-western India, experiences winter. Cooler conditions lead to development of relatively higher pressure over north-western India. The hot, dry 'loo' is a summer phenomenon, so (a) is the correct choice.

Q2: Answer the following questions in about 30 words.
(i) What is the Inter-Tropical Convergene Zone?
Ans: The Inter-Tropical Convergence Zone (ITCZ) is a belt of low pressure near the equator where the trade winds of both hemispheres converge. Convergence forces air to rise, producing frequent convection and heavy rainfall.

(ii) What is meant by 'bursting of monsoon'? Name the place of India which gets the highest rainfall.
Ans: 'Bursting of monsoon' refers to the sudden and vigorous onset of monsoon rains marked by heavy showers, thunder and lightning when moisture-laden winds arrive. Mawsynram in Meghalaya receives the highest annual rainfall in India.

(iii) Which type(s) of cyclones cause rainfall in north-western India during winter? Where do they originate?
Ans: Western cyclonic disturbances cause winter rainfall in north-western India. They originate over the Mediterranean Sea and move eastwards across West Asia before reaching India.

Q3: 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: India shows a broad climatic unity because the monsoon system affects most of the country, but there are significant regional variations in temperature, rainfall and seasonality. These variations arise from latitude, altitude, distance from the sea and local relief. Examples include:

• Temperature: The summer temperature may reach about 50-55°C in parts of western Rajasthan while high-altitude areas like Leh may record very low winter temperatures (around -45°C). On the same summer day, a hill station such as Tawang may have much cooler weather (about 19°C), illustrating strong regional contrasts.
• Rainfall: Places in the Khasi Hills such as Cherrapunji and Mawsynram receive over 1,080 cm of rain annually, whereas arid locations like Jaisalmer in Rajasthan receive less than 10 cm in a year, showing extreme differences in precipitation.
• Monsoon behaviour: The Ganga delta and coastal Orissa face frequent rain-bearing storms in July-August, while the Coromandel Coast, some distance to the south-east, may remain relatively dry during the same period. These examples show how the monsoon's impact varies regionally.

(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: The Indian Meteorological Department recognises the following four seasons:
(i) The cold weather season
(ii) The hot weather season
(iii) The south-west monsoon season
(iv) The retreating monsoon season

The Cold Weather Season:

• It starts by mid-November in northern India and continues through December and January, which are the coldest months. Mean daily temperatures often remain below 21°C in many places, and nighttime temperatures can fall close to or below freezing in parts of Punjab, Himachal Pradesh and Rajasthan.
• The peninsular region does not experience a pronounced cold season; coastal areas show little seasonal change in temperature because of the moderating influence of the sea and their proximity to the equator. Northeasterly wind flows are more common over parts of the country during this season.
• Overall weather is generally pleasant in winter, but from time to time it is disturbed by shallow cyclonic depressions known as western disturbances. These systems originate near the Mediterranean Sea and travel eastwards across West Asia, bringing cloudiness and rainfall or snow to north-western India.