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Page No 39:
Question 1:
Choose the right answer from the four alternatives given below.
(i) Which one of the following places receives the highest rainfall in the world?
(a) Silchar
(c) Cherrapunji
(b) Mawsynram
(d) Guwahati
(ii) The wind blowing in the Northern Plains in the summers is known as
(a) Kaal Baisakhi
(c) Trade Winds
(b) Loo
(d) None of the above
(iii) Which one of the following causes rainfall during winters in north-western part of India?
(a) Cyclonic depression
(c) Western disturbances
(b) Retreating monsoon
(d) Southwest monsoon
(iv) Monsoon arrives in India approximately in
(a) Early May
(c) Early June
(b) Early July
(d) Early August
(v) Which one of the following characterises the cold weather season in India?
(a) Warm days and warm nights
(c) Cool days and cold nights
(b) Warm days and cold nights
(d) Cold days and warm nights
ANSWER:
(i) (b) Mawsynram
(ii) (b) Loo
(iii) (c) Western disturbances
(iv) (c) Early June
(v) (c) Early June
Page No 39:
Question 2
Answer the following questions briefly.
(i) What are the controls affecting the climate of India?
(ii) Why does India have a monsoon type of climate?
(iii) Which part of India does experience the highest diurnal range of temperature and why?
(iv) Which winds account for rainfall along the Malabar Coast?
(v) What are jet streams and how do they affect the climate of India?
(vi) Define monsoons. What do you understand by “break” in monsoon?
(vii) Why is the monsoon considered a unifying bond?
ANSWER:
(i) The factors affecting the climate of India are:
1. Latitude 2. Altitude 3. Pressure and Winds
(ii) The climate of India is strongly influenced by monsoon winds. Hence, it has a monsoon type of climate.
(iii) The regions experiencing this phenomenon are in the northwestern part of India. T he reason behind this effect is the Thar desert. Moreover, this region does not have an ocean to moderate the temperature.
(iv) Southwest monsoon winds are responsible for rainfall along the Malabar Coast.
(v) 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 k m/h in winter. A number of separate jet streams have been identified. The most constant is the midGeography Chapter 4 Climate latitude and subtropical jet stream. They cause depressions during the monsoon season.
(vi) Monsoon refers to the complete reversal of winds over a large area leading to a change of seasons.
“Break” in monsoon refers to the wet and dry spells of the monsoon. In other words, the monsoon rains take place for a few days at a time. They are interspersed with rainless intervals.
(vii) Despite variations in temperature conditions across India, a sense of unity is imposed by the monsoon. The seasonal alteration of the wind systems and the associated weather conditions provide a rhythmic cycle of seasons that binds the entire country.
Page No 39:
Question 3:
Why does the rainfall decrease from the east to the west in Northern India?
ANSWER:
As they move in the direction, the winds lose the moisture content. Hence the reason for the reduction in rainfall.
Page No 39:
Question 4.
Give reasons as to why.
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent?
(ii) The bulk of rainfall in India is concentrated over a few months.
(iii) The Tamil Nadu coast receives winter rainfall.
(iv) 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:
(i) 1.Seasonal change in wind direction due to pressure difference.
2.El-Nino plays a major role.
(ii) Rainfall is dependent on the South West Monsoon winds, it rapidly progresses and covers large swathes of the country by July.
(iii) It is be cause of NorthEast monsoon winds.
(iv) The Bay of Bengal faces frequent pressure changes.
(v) Because they fall in the rain shadow region of Aravali Mountains.
Page No 40:
Question 5:
Describe the regional variations in the climatic conditions of India with the help of suitable examples.
ANSWER:
1. The cold weather season begins from midNovember in norther n 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
2. In March, the highest temperature is about 38° Celsius, recorded on the De ccan 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.
Page No 40:
Question 6:
Discuss the mechanism of monsoons.
ANSWER:
(a) The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.
(b) The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator. It is also known as the monsoon‐trough during the monsoon season).
c) The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high pressure area affects the Indian Monsoon.
(d) The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.
(e) The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.
Page No 40:
Question 7:
Give an account of weather conditions and characteristics of the cold season.
ANSWER:
The Cold Weather Season
Beginning from mid-November, the winter season lasts till February. The weather is usually marked by clear sky, low temperatures and low humidity, and feeble and variable winds. The temperature decreases from the south to the north, with the peninsular region not showing any noticeable seasonal change in temperature pattern due to the moderating influence of the sea. The coldest months are December and January. The days are generally warm and the nights are cold. Frost is common in the north and the higher slopes of the Himalayas experience snowfall.
During this season, the sub-tropical westerly jet streams blowing south of the Himalayas bring in cyclonic disturbances from the Mediterranean region. These cause winter rains over the plains and snowfall in the mountains. The Tamil Nadu coast also receives winter rainfall due to the blowing of the north-east trade winds from sea to land.
Page No 40:
Question 8:
Give the characteristics and effects of the monsoon rainfall in India.
ANSWER:
Characteristics of monsoon rainfall in India:
(i) The duration of the monsoon is between 100 to 120 days from early June to mid-September.
(ii) Around the time of its arrival, the normal rainfall increases suddenly and continues for several days. This is known as the ‘burst’ of the monsoon.
(iii) The monsoon has characteristic wet and dry spells or ‘breaks’ in rainfall. The monsoon rains take place only for a few days at a time. They are interspersed with rainless intervals.
(iv) The moisture is carried by pulsating south westerlies that are affected by different atmospheric conditions, thereby giving monsoon rains an uncertain character. The annual rainfall is highly variable from year to year
(v) The rainfall is unevenly distributed across the Indian landscape. Parts of the western coast and north-eastern India receive the maximum rainfall. Regions such as parts of Rajasthan, Gujarat, Leh and the leeward side of the Western Ghats receive very little rainfall.
Effects of monsoon rainfall in India:
(a) Indian agriculture is largely dependent upon the water from the monsoon rains. Late, low or excessive rains have a negative impact upon crops.
(b) Due to the uneven distribution of rainfall across the country, there are some regions that are drought prone and some that are flood afflicted.
(c) The monsoon provides India with a distinct 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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