- Climate
NCERT Questions:
- Choose the correct answer from the four alternatives given below:
(i) Which one of the following places receives the highest rainfall in the world?
a) Silchar
b) Mawsynram
c) Cherrapunji
d) Guwahati
Ans. b) Mawsynram
Mawsynram is a place in Khasi hills of Meghalaya.
(ii) The wind blowing in the Northern Plains in summers is known as:
a) Kal Baisakhi
b) Loo
c) Trade winds
d) None of the above
Ans. b) Loo
Loo is a hot wind that blows in northern part of India.
(iii) Which one of the following causes rainfall during winters in north western part of India.
a) Cyclonic depression
b) Retreating monsoon
c) Western disturbances
d) South West Monsoon
Ans. c) Western disturbances
Western cyclonic disturbances are the weather phenomena of the winter months brought in by westerly flow from the Mediterranean region.
(iv) Monsoon arrives in India, approximately in:
a) Early May
b) Early July
c) Early June
d) Early August
Ans. c) Early June
By early June the low pressure conditions over the northern plains intensifies and attracts monsoon winds.
(v) Which one of the following characterises the cold weather season in India:
a) Warm days and warm nights
b) Warm days and cold nights
c) Cold days and cold nights
d) Cold days and warm nights
Ans. b) Warm days and cold nights
- Answer the following questions briefly:
(i) What are the controls affecting the climate of India?
Ans. There are six major controls of climate of any place. They are:
- a) Latitude
- b) Altitude
- c) Pressure and wind system
- d) Distance from the sea
- e) Ocean currents
- f) Relief features
(ii) Why does India have a monsoon type of climate?
a) The monsoon type of climate is characterized by a distinct seasonal pattern. The weather conditions greatly change from one season to the other.
b) These changes are particularly noticeable in the interior parts of the country.
c) The coastal areas do not experience much variation in temperature, though there is variation in rainfall pattern.
Four main seasons can be identified in India:
i) The cold weather season
ii) The hot weather season
iii) The advancing monsoon
iv) The retreating monsoon, with some regional variations
(iii) Which part of India does experience the highest diurnal range of temperature and why?
Ans. The Thar Desert in India has the highest diurnal range of temperature. Sand heats up quickly and also cools down quickly, hence, impacting the temperature of the region.
(iv) Which winds account for rainfall along the Malabar Coast?
Ans. Surface winds account for rainfall along the Malabar Coast.
(v) What are jet streams and how do they affect the climate of India?
Ans.
a) Jet streams are narrow belt of high altitude above 1200 metre. Westerly winds in the troposphere.
b) Their speed varies from about 110 kilometre/ hr. in summer to about 184 Km/ hr. in winters.
c) A number of separate jet streams have been identified.
d) Over India, these jet streams blow south of the Himalayas all through the year except in summer.
e) The western cyclonic disturbances experienced in the north and north western parts of the country are brought in by this westerly flow.
f) In summer, the subtropical westerly jet stream moves north of the Himalayas with the apparent movement of the sun.
g) And easterly jet stream, called the Tropical Easterly Jet stream blows over peninsular India. Approximately over 14˚ North during the summer months.
(vi) Define monsoon. What do you understand by break in monsoon?
Ans.
a) A seasonal reversal in wind direction during a year is called monsoon.
b) Monsoon tends to have breaks in rainfall which means that there are wet and dry spells in between.
c) The monsoon rains take place only for a few days at a time, and then come the rainless intervals.
(vii) Why the monsoon is considered a unifying bond?
Ans.
a) Despite great moderating influences on the climate of India, there are great variations in the temperature conditions.
b) Nevertheless, the unifying influence of the monsoon on the Indian subcontinent is quite perceptible.
c) The seasonal alteration of the wind system and the associated weather conditions provide a rhythmic cycle of seasons.
- Why does the rainfall decrease from the east to the west in northern India?
Ans.
a) The western coast and north eastern India receive over about 400 centimeter of rainfall annually.
b) However, it is less than 60 centimeter in western Rajasthan and adjoining parts of Gujarat, Haryana and Punjab.
c) Rainfall is equally low in the interior of the Deccan Plateau and east of the Sahyadris.
d) A third area of low precipitation is around Leh in Ladakh.
e) The rest of the country receives moderate rainfall.
f) Snowfall is a restricted to the Himalayan region.
g) Going to the nature of monsoons, the annual rainfall is highly variable from year to year.
h) Variability is high in the regions of low rainfall, such as parts of Rajasthan, Gujarat and the leeward side of the Western Ghats.
i) As such, while areas of high rainfall are liable to be affected by floods, areas of low rainfall are drought prone.
- Give reasons as to Why?
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent…
a) Characteristic feature of the cold weather season over the northern plains is the inflow of cyclonic disturbances from the West and North West.
b) These low pressure systems originate over the Mediterranean Sea and Western Asia and move into India along with the westerly flow.
c) They cause much needed winter rains over the plains and snowfall in the mountains.
d) Although the total amount of winter rainfall locally known as ‘mahawat’ is small they are of immense importance for the cultivation of Rabi crops.
e) The peninsula region does not have a well-defined cold season.
f) There is hardly any noticeable seasonal change in temperature pattern during winters due to the moderating influence of the sea.
(ii) The bulk of rainfall in India is concentrated over a few months…
a) The inflow of the southwest monsoon into India brings about the total change in the weather.
b) Early in the season, the windward side of the Western Ghats receive very heavy rainfall. More than 250 cm. The Deccan Plateau and parts of Madhya Pradesh also receive some amount of rain in spite of lying in the rain shadow area.
c) The maximum rainfall of this season is received in the north eastern part of the country.
d) Mawsynram in the southern ranges of the Khasi Hills receives the highest average rainfall in the world.
e) Rainfall in the Ganga valley decreases from the east to the west.
f) Rajasthan and parts of Gujarat get scanty rainfall.
g) The Tamil Nadu coast receives winter rainfall.
(iii) The Tamil Nadu coast receives winter rainfall…
a) In the winter season, North East trade winds prevail over the country.
b) They blow from land to sea and hence for most part of the country, it is a dry season.
c) Some amount of rainfall occurs on the Tamil Nadu coast from these winds as here they blow from sea to land.
(iv) The delta region of the eastern coast is frequently struck by the cyclones…
a) The delta region of the eastern coast is frequently struck by the cyclones. The low pressure conditions over north western India get transferred to the Bay of Bengal by early November.
b) This shift is associated with the occurrence of cyclonic depressions. That originates over the Andaman Sea.
c) These cyclones generally cross the eastern coast of India, cause heavy and widespread rain.
d) These tropical cyclones are often very destructive.
e) The ’thickly populated deltas of the Godavari, the Krishna and the Kaveri are frequently struck by cyclones. That causes great damage to life and property.
f) Sometimes these cyclones arrive at the coast of Orissa, West Bengal and Bangladesh.
(v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought prone…
a) Going to the nature of monsoon the annual rainfall is highly variable from year to year.
b) Variability is high in the regions of low rainfall, such as the parts of Rajasthan, Gujarat and the leeward side of the Western Ghats.
c) As such, while areas of high rainfall are liable to be affected by floods, areas of low rainfall are drought prone.
- Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Ans. Despite an overall unity in the general pattern, there are perceptible regional variations in climatic conditions within the country.
a) The two important elements which cause these variations are temperature and precipitation. Eg. In summer, the mercury occasionally touches 50˚C in some parts of Rajasthan desert whereas it may be around 20˚C in Pahalgam in Jammu and Kashmir.
b) On a winter night, temperature at Drass in Leh may be as low as -45˚ C. Thiruvananthapuram, on the other hand, may have a temperature of 22 ˚ C.
- Discuss the mechanism of monsoon.
Ans. To understand the mechanism of monsoon, the following facts are important:
a) The differential heating and cooling of land and water creates low pressure on the landmarks 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, 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 high 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.
- Give an account of weather conditions and characteristics of the cold season.
Ans.
a) The weather conditions greatly change from one season to other.
b) These changes are particularly noticeable in the interior parts of the country.
c) The coastal areas do not experience much variation in temperature. Though there is variation in rainfall pattern.
d) The cold weather season begins from mid-November in northern India and stays till February.
e) December and January are the coldest months in the northern part of India.
f) The temperature decreases from South to the north.
g) The average temperature of Chennai on the eastern coast is between 24˚ – 25˚ C.
h) Days are warm and nights are cold. Frost is common in the north, and the higher slopes of the Himalayas experience snowfall.
- Give the characteristics and effects of the monsoon rainfall in India.
Ans.
a) The monsoon unlike the trade winds, are not steady but are pulsating in nature. Affected by different atmospheric conditions and countered by it on its way over the warm tropical seas.
b) The duration of the monsoon is between 100 to 120 days from early June to mid- September. Around the time of its arrival, the normal rainfall increases suddenly and continues constantly for several days.
c) This is known as the burst of the monsoon and can be distinguished from the pre monsoon showers.
d) The monsoon arrives at the southern tip of the Indian peninsula generally by the first week of June.
e) Subsequently, it divides into two the Arabian Sea branch and the Bay of Bengal branch.
f) The Arabian Sea branch reaches Mumbai about 10 days later, on approximately the 10th of June. This is a fairly rapid advance.
g) The Bay of Bengal branch also advances rapidly and arrives in Assam in the first week of June. The lofty mountains caused the monsoon winds to deflect towards the West over the Ganga plains. By mid-June, the Arabian Sea branch of the monsoon arrives over Saurashtra, Kutch and the central part of the country.
h) The Arabian Sea and Bay of Bengal branches of the monsoon merge over the north western part of the Ganga planes.
i) Delhi generally receives the monsoon showers from the Bay of Bengal branch by the end of June. Tentative date is 29th of June. By the first week of July, western Uttar Pradesh, Punjab, Haryana and eastern Rajasthan experience the monsoon.
j) By mid-July, the monsoon reaches Himachal Pradesh and the rest of the country. Withdrawal or the retreat of the monsoon is a more gradual process.
k) The withdrawal of the monsoon begins in North western states of India by early September.
l) By mid-October, it withdraws completely from the northern half of the peninsula.
m) The withdrawal from the southern half of the peninsula is fairly rapid. By early December, the monsoon has withdrawn from the rest of the country.
n) The Islands receive the very first monsoon showers progressively from south to north from the first week of April to the first week of May.
o) The withdrawal takes place progressively from north to South. From the first week of December to the first week of January, by this time, the rest of the country is already under the influence of winter monsoon.
Extra Questions:
- What does the word monsoon imply?
Ans. The word monsoon comes from the Arabic word ‘Mausim’. which means seasons. It implies a seasonal reversal in the wind direction throughout the year.
- What is burst of monsoon?
Ans. Around the time of its arrival the normal rainfall increases suddenly and continues constantly for several days this is known as the burst of monsoon.
- Name the wind which prevails over India in winter season?
Ans. North-eastern trade winds prevail over India in winter season.
- State chief characteristics of the western disturbances?
Ans. Western disturbances originate over the East Mediterranean Sea. These also cause winter shower in North India named as ‘Mahavat’. It is good for rabi crops.
- Name two states where Mango shower is common?
Ans. Mango shower is common in Kerala and Karnataka.
- Name the wind from which the Tamil Nadu receive winter rainfall.
Ans. It is the reversal of monsoon or northeast monsoon which reaches these areas after passing over Bay of Bengal and taking moisture from there. Hence Tamil Nadu receive rainfall in the month of October and November.
- What is retreating monsoon?
Ans. During the month of October and November the temperature in the Northern Plains begins to decrease.
Due to this low temperature, the pressure starts rising and the low pressure is no longer strong enough to attract the monsoon winds.
This results in the retreat of the monsoon.
- Name the two branches of the monsoon.
Ans. The Arabian Sea branch and the Bay of Bengal branch are the two branches of monsoon in India.
- Which region of India receives most of its rainfall in winter?
Ans. Tamil Nadu Coast receives most of its rainfall in winter season.
- Explain the development of monsoon and its influence over rainfall distribution.
Ans. It is a region of low atmospheric pressure which develops because of excessive heat in Northern Plains and at the same time high pressure develops near Somalia in the Indian Ocean.
a) It brings a remarkable change in rainfall pattern.
b) These low-pressure regions attract the moisture laden wind from Arabian Sea and Bay of Bengal.
c) It is responsible for dry and wet spells of the monsoon.
- During which season the cyclones develop in Bay of Bengal?
Ans. During retreating monsoon or withdrawal of monsoon cyclones developed in the Bay of Bengal.
- How does climate affect the life of the people of a place?
Ans. The cycle of seasons in India has greater impact on the life of the people living in this country. Crops festivals occupations costumes etc. are highly influenced by the change of seasons.
- Why does the peninsular region not experience very hot summer?
Ans.
a) Sea or large water bodies has a moderating effect on temperature of a place close to it.
b) The Indian Peninsula is surrounded by water bodies.
c) During the day the sun heats the land and the water in seas and oceans.
d) The water takes longer to heat up in summer and longer to cool down in winters in comparison to land so the places near the sea have a moderate climate throughout the year.
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