NCERT Folder 9th Geography Chapter 4 : Climate

Geography

Class 9

Chapter 4

Climate

Revision Notes

Important Terms

  • Climate : General weather conditions over a period of thirty years is said to be the climate of a place.
  • Elements of weather : Temperature, atmospheric pressure, wind, humidity and precipitation are elements of weather and climate.
  • Monsoon : Monsoon is basically a seasonal reversal in the wind through the year.
  • South-west monsoons : Winds move from the high-pressure area over the southern Indian Ocean, cross the Equator and turn right towards the low-pressure areas over the Indian subcontinent. These winds are known as the south-west monsoon winds.
  • Subtropical westerly jet streams : The most constant are the mid-latitude and the sub-tropical jet streams. They originate from the Mediterranean region and are known as subtropical westerly jet streams.
  • Easterly jet stream : An easterly jet stream, called the tropical easterly jet stream, blows over peninsular India, approximately over 14°N during the summer months.
  • Currents : The movement of water in the oceans is called currents.
  • Coriolis force : It is an apparent force caused by the earth’s rotation. This force deflects winds towards the right in the Northern Hemisphere and towards the left in the Southern Hemisphere.
  • Weather : Weather is the state of the atmosphere of a particular area at any point of time in context to heat, cloudiness, dryness, sunshine, wind, rain, etc.
  • Atmospheric conditions : Atmospheric conditions describes the weather include elements like temperature, precipitation, pressure, wind and humidity.
  • Climate controls : The interplay of latitude, altitude, distance from the sea, pressure and wind system, ocean currents and relief features determine climatic conditions of a place.
  • Altitude : Altitude refers to the height of a place above the sea level.
  • Continentality : As the distance from the sea increases, the weather conditions become extreme. Places away from the sea have very hot summers and very cold winters. This condition is known as continentality.
  • Southern Oscillation : Changes in pressure over the southern oceans also affect the monsoons. In certain years, there is a reversal in the pressure conditions. This periodic change in pressure conditions is known as the Southern Oscillation or SO.
  • Burst of Monsoon : The monsoon arrives with a sudden downpour of rainfall that continues for several days. This is known as the ‘burst’ of the monsoon.
  • Mahawat : The winter rainfall is locally known as Mahawat.
  • Frost : A state in freezing, frozen dew.
  • Loo : ‘Loo’ are strong, gusty, hot, dry winds that blow during the day over north and north-western India.
  • Mango Showers : Pre -monsoon showers are often referred to as ‘mango showers,’ as they help in the early ripening of mangoes.
  • Advancing monsoon : An advancing monsoon in India refers to the rainy season that lasts for a period of four months from June to September.
  • Retreating monsoon : The retreating monsoon refers to the transition season that lasts from October to December.
  • October Heat : The months of October-November form a period of transition from the hot rainy season to dry winter conditions. The main cause of this transition is the movement of the sun towards the south. By the beginning of October, the monsoon withdraws from the Northern Plains. The retreating monsoon season is marked by clear skies and a rise in the temperatures. The land is still moist and the weather becomes hot and humid. The days can become quite oppressive. This is commonly known as ‘October Heat’.

Summary

Climate Of India

  • Weather describes the day-to-day meteorological conditions such as wind, temperature, cloudiness, moisture, rainfall, etc., affecting a place. Climate is the average weather, usually taken over 30-years period for a particular region and time. The basic elements of weather are wind, temperature, air pressure, precipitation and moisture.
  • ‘Monsoon’ refers to the seasonal reversal in the wind direction during the year. The two important elements of climate are temperature and precipitation.
  • In some parts of Rajasthan desert, the temperature in summers is 50°C, whereas summer temperature in Jammu and Kashmir is 20°C. During winters, the temperature in Jammu and Kashmir may be –45°C. Drass in Jammu and Kashmir is the second coldest inhabited place in the world.
  • In India, the Tropic of Cancer passes through the central part of the country, from the Rann of Kutch in the west to Mizoram in the east. India has both tropical and subtropical types of climate.
  • Contrasts in temperature are experienced more in the interior of the country. The rainfall in India varies in its form, types, amount and seasonal distribution. In the upper parts of the Himalayas, precipitation is mostly in the form of snowfall, whereas the remaining parts of the country receive rains. There is a decrease in the rainfall generally from east to west in the Northern Plains. Climatic variations also affect the way people live, i.e. depends on the food, the clothes and the kind of houses they live in.
  • In India, the elevation of land ranges from 30 metres to 6,000 metres. The Himalayan mountains to the north of India have an average height of about 6,000 metres. The average summer temperature on the Himalayas can vary from 0°C to 14°C, while winters can see the temperature dipping below freezing point along with heavy snowfall.
  • The Himalayas prevent the cold winds from Central Asia from entering the subcontinent. The rainfall in India is governed mainly by pressure and surface winds, upper air circulation and western cyclonic disturbances and tropical cyclones.
  • Due to the Coriolis force, these winds move on towards the equatorial low-pressure area. The Coriolis force also known as ‘Ferrel’s Law,’ is an apparent force caused by the earth’s rotation. This force deflects winds towards the right in the Northern Hemisphere and towards the left in the Southern Hemisphere.
  • The north-easterly winds are land-bearing winds; hence they carry very little moisture and bring little or no rain in India.
  • During winter, a high-pressure area is created in the north of the Himalayas. In summer, a low-pressure area develops over interior Asia as well as over north-western India. This causes a complete reversal of the direction of winds during summer.
  • Winds move from the high-pressure area over the southern Indian Ocean, cross the Equator and turn right towards the low-pressure areas over the Indian subcontinent. These winds are known as the south-west monsoon winds.
  • An important component of the flow is the jet stream. Jet streams are a narrow belt of high altitude westerly winds that blow in the troposphere. Their speed varies from about 110 kilometres per hour in summer to about 184 kilometres per hour in winter.
  • A number of separate jet streams have been identified. The most constant are the mid-latitude and the subtropical jet streams. They originate from the Mediterranean region and are known as subtropical westerly jet streams. An easterly jet stream, called the tropical easterly jet stream, blows over peninsular India, approximately over 14°N during the summer months. The movement of water in the oceans is called currents.

Climate Control

  • The day-to-day changes that we experience are referred to as weather. Weather is the state of the atmosphere of a particular area at any point of time. Atmospheric conditions that describe the weather include elements like temperature, precipitation, pressure, wind and humidity.
  • During a year, the weather changes in cycles, the cyclic changes in the atmospheric conditions are called seasons. By observing the weather pattern for longer periods, usually over 30 years, the climate of a place can also be determined. The basic elements of weather are wind, temperature, air pressure, precipitation and moisture.
  • Climate describes the long-term pattern of weather that generally prevails over an area. Based on climatic differences, the world can be divided into a number of climatic regions. Each climatic region has its own characteristic vegetation and wildlife. The climatic conditions also influence the lifestyles of the people living in these regions.
  • The factors affecting the climate of a place are referred to as controls and are latitude, altitude, pressure and wind system, distance from the sea, ocean currents and relief features.
  • Altitude is another factor controlling the climate of a place. Altitude refers to the height of a place above sea level. The higher one travels into the troposphere, the lower the temperature becomes. The rate at which the temperature drops is known as the lapse rate.
  • The variations in air temperature control the pressure and wind system of a place. Warm air rises, creating low pressure areas, while cold air sinks, creating high pressure areas. As a result, winds blow outward from a high pressure location towards lower pressures.
  • The differences in air pressures near the Equator and the poles are the main factors that influence global pressure and wind systems. In India, the Tropic of Cancer passes through the central part of the country, from the Rann of Kutch in the west to Mizoram in the east. India has both tropical and subtropical types of climate.
  • The distance of a place from the sea is another important factor that regulates the climate of a place.
  • As the distance from the sea increases the weather conditions become extreme. Places away from the sea have very hot summers and very cold winters. This condition is known as continentality.
  • Another important control of climate is the circulation of water and air. The air in the atmosphere and the water in the oceans are in constant motion, distributing heat around the world in regular patterns. Warm air and water move towards the poles, while cool air and water move towards the equator.
  • Another major control of climate is the relief of a place. Mountains often act as natural barriers for wind and moisture, affecting the climate of the areas around it.
  • The Himalayas influence the climate of the Indian subcontinent by protecting it from the cold air mass of Central Asia.
  • The climate and related weather conditions in India are controlled by the following atmospheric conditions : Pressure and surface winds, upper air circulation, western cyclonic disturbances and tropical cyclones.

Mechanisms Of Monsoon

  • The climate of India is strongly influenced by the monsoon winds. It refers to a season in which the wind system reverses completely. The monsoons are experienced in the tropical area roughly between 20°N and 20°S.
  • Various atmospheric conditions influence the monsoon winds.
    • The first condition is the differential heating and cooling of land and water. This creates low pressure on the landmass, while high pressure is created over the seas around during day time, but is reversed during the night time.
    • The second condition is the shift in the position of Inter-Tropical Convergence Zone (ITCZ). In summer, the equatorial trough, normally positioned about 5°N of the Equator, moves over the Ganga plain creating a monsoon trough during the monsoon season.
    • The third condition is the presence of the high-pressure area that develops east of Madagascar. It is approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affects the Indian Monsoon.
    • The fourth condition develops during the summer. The Tibetan Plateau gets intensely heated resulting in strong vertical air currents and high pressure over the plateau about 9 km above sea level.
    • The fifth condition develops during the summer due to the movement of the westerly jet streams to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian Peninsula.
  • Changes in pressure over the southern oceans also affect the monsoons. In certain years, there is a reversal in the pressure conditions. This periodic change in pressure conditions is known as the Southern Oscillation, or SO.
  • The Southern Oscillation is connected to El Nino, which is a warm ocean current that flows past the Peruvian Coast. It flows every two to five years in place of the cold Peruvian current. The phenomenon is referred to as ENSO (El Nino Southern Oscillations). In India, the monsoon lasts for 100 to 120 days from early June and to mid-September. The monsoon winds encounter various atmospheric conditions on their way and hence are pulsating in nature, and not steady.
  • The monsoon arrives with a sudden downpour of rainfall that continues for several days. This is known as the ‘burst’ of the monsoon.
  • The monsoon arrives at the southern tip of the Indian Peninsula generally by the first week of June. By early September, the monsoon starts to withdraw or retreat and is a more gradual process. By mid-October, it withdraws completely from the northern half of the Peninsula. The withdrawal takes place progressively from north to south from the first week of December to the first week of January. This is the start of the winter season.
  • The retreating monsoon winds move over the Arabian Sea and the Bay of Bengal, and collect moisture on the way. These monsoon winds reach the southern states of India by October, and are responsible for a second round of rainfall. These are called the winter monsoons. The winter monsoon is experienced in the states of Tamil Nadu, Kerala and Andhra Pradesh in the first week of January.

The Seasons Of India

  • The changes in weather conditions of India can be broadly categorised into four distinct patterns. These are the cold weather season, the hot weather season, the advancing monsoon and the retreating monsoon.
  • India has cold weather in the winter that begins in mid-November and lasts till February. The northern parts of India are the first to experience the cold. December and January are the coldest months in northern India. The southern parts of India do not experience very low temperatures.
  • Frost is a common phenomenon in the north plains, while the higher slopes of the Himalayas experience snowfall.
  • During winter, the north-east trade winds blow over the country. In most parts of India, the weather during the winter is dry. In some parts, like the coast of Tamil Nadu, the winds blow from the sea to the land. Hence, these places receive some amount of rainfall during the winter.
  • Other characteristic feature of the winter season experienced over the northern plains is the inflow of cyclonic disturbances from the west and the north-west. The winter rainfall is locally known as Mahawat.
  • The sea has a moderating influence over the peninsular region of India. Hence, there are no drastic seasonal variations in temperature pattern, and winters are not as distinct as in the north. The hot weather season in India refers to the summers that begin in March and lasts till mid-June.
  • In India, summer is caused due to the apparent northward movement of the sun, which shifts the global heat belt northward. ‘Loo’ are strong, gusty, hot, dry winds that blow during the day over north and north-western India.
  • In northern India, dust storms are also very common during the month of May. This is also the season for localised thunderstorms, associated with violent winds, torrential downpours, often accompanied by hail. Pre -monsoon showers are common, especially in Kerala and Karnataka and are often referred to as ‘mango showers,’ as they help in the early ripening of mangoes.
  • The advancing monsoon in India refers to the rainy season that lasts for a period of four months from June to September. The trade winds from the southern hemisphere, which originate over the warm subtropical areas of the southern oceans, bring the south-west monsoon winds into India.
  • Another characteristic feature of the monsoon is the ‘breaks’ in rainfall and refers to the alternating wet and dry spells of rains. The Indian monsoon is very unpredictable. These breaks occur due to the movement of the monsoon trough.
  • The farming schedule of millions of farmers all over the country, which is dependent on the monsoons, can sometimes get disturbed. The retreating monsoon refers to the transition season that lasts from October to December.
  • The months of October-November form a period of transition from the hot rainy season to dry winter conditions. The main cause of this transition is the movement of the sun towards the south. By the beginning of October, the monsoon withdraws from the Northern Plains. The retreating monsoon season is marked by clear skies and a rise in the temperatures. The land is still moist and the weather becomes hot and humid. The days can become quite oppressive. This is commonly known as ‘October heat’.
  • Due to the unpredictable nature of the monsoon, the distribution of rainfall varies drastically from region to region. Major variations can also be seen in the annual precipitation from year to year. The phenomenon of monsoon is an integral part of the Indian landscape, animal and plant life, agricultural calendar, and the life of the people and their festivities.

Intext Questions

Find Out

(Page No. 27)

Question.1. Find out why the houses in Rajasthan have thick walls and flat roofs.
Answer. Houses in Rajasthan have thick walls and flat roofs. The thick walls do not allow the heat to get into the houses while the flat roofs help to retain the little water that comes as rain in the desert (water harvesting).

Question.2. Find out why is it that the houses in the Tarai region and in Goa and Mangalore have sloping roofs.
Answer. The houses in Tarai region, Goa and Mangalore have sloping roofs so that the rainwater due to heavy rains in these area flow off the roof.

Question.3. Why are houses in Assam built on stilts?
Answer. The houses are built on stilts in Assam as there is danger of floods and wild animals in large areas of Assam.

Find Out

(Page No. 27)

Question.1. Why most of the world’s deserts are located in the western margins of continents in the subtropics?
Answer. Sometimes the presence of cold coastal water can contribute to the creation of a desert along the adjoining shore. This occurs because cold ocean currents tend to stabilise the air over the coast and inhibit cloud formation. Large western coastal deserts include the Atacama Desert in Chile and the Namib Desert in Namibia.

Activity

(Page No. 38)

Question.1.Activity-geo-09-chapter-4
(i) On the basis of the news items above, find out the names of places and the seasons described.
Answer.

  • Chennai- rainy season,
  • Mumbai- rainy season,
  • Kashmir-winter,
  • Delhi-summer,
  • Srinagar- winter,
  • Amritsar- winter,
  • Shimla- winter.

(ii) Compare the rainfall description of Chennai and Mumbai and explain the reasons for the difference.
Answer.

  • In Chennai, much of the fury was unleashed by the Adyar river. As water from the Chembarambakkam reservoir was released into the river, whose depth and width had shrunk due to rapid urbanization and encroachments, it disgorged water into the neighborhoods along the banks.
  • In Mumbai, the thick slush-filled stench-emanating rivulet, the Mithi, which stretches from Powai Lake in the eastern suburbs to the Mahim Creek in the western part, was once a river that flowed out into the Arabian Sea. Like Adyar, Mithi too was lined with encroachments.
  • Owing to massive concretization of roads and unplanned constructions that have flattened the natural topography, almost 90 to 100 per cent of the rainwater in both cities drains off into the storm water drains instead of being absorbed into the ground.

(iii) Evaluate flood as a disaster with the help of a case study.
Answer.

Kerala flood case:

  • The Indian state of Kerala receives some of India’s highest rainfall during the monsoon season. However, during 2018 the state experienced its highest level of monsoon rainfall in decades. According to the India Meteorological Department (IMD), there was 2346.3 mm of rainfall, instead of the average 1649.55 mm.
  • Kerala received over two and a half times more rainfall over the average for August. Between August 1 and 19, the state received 758.6 mm of rainfall, compared to the average of 287.6 mm, or 164% more. This was 42% more than during the entire monsoon season.
  • In some areas, floodwater was between 3-4.5 m deep. Floods in the southern Indian state of Kerala killed more than 410 people since June 2018 in what local officials said was the worst flooding in 100 years. Many of those who died had been crushed under debris caused by landslides. More than 1 million people were left homeless in the 3,200 emergency relief camps set up in the area.
  • Parts of Kerala’s commercial capital, Cochin, were underwater, snarling up roads and leaving railways across the state impassable. The state’s airport, which is used by domestic and overseas tourists, was closed, causing major disruption.
  • Local plantations were inundated by water, endangering the local rubber, tea, coffee and spice industries.
  • Schools in all 14 districts of Kerala were closed, and some districts have banned tourists because of safety concerns.
  • Maintaining sanitation and preventing disease in relief camps housing more than 800,000 people was a significant challenge. Authorities also had to restore regular supplies of clean drinking water and electricity to the state’s 33 million residents.

NCERT Solution

(Page No. 15)

Question.1. Choose the right answer from the four alternatives given below :
(i) Which of the following places receives the highest rainfall ?
(a) Guwahati
(b) Mawsynram
(c) Kolkata
(d) None of these
Ans. (b) Mawsynram

(ii) The wind blowing in the northern plains in summers is known as:
(a) Kaalbaisakhi
(b) Loo
(c) Trade winds
(d) None of the above
Ans. (b) Loo

(iii) Which one of the following causes rainfall during winters in northwestern part of India?
(a) Cyclonic depression
(b) Retreating monsoon
(c) Western disturbances
(d) Southwest monsoon
Ans. (a) Cyclonic depression

(iv) Monsoon arrives in India approximately in:
(a) Early May
(b) Early July
(c) Early June
(d) Early August
Ans. (c) Early June

(v) Which one of the following characterises the cold weather in India?
(a) Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights
Ans. (c) Cool days and cold nights

Question.2. Answer the following questions briefly.
(i) What are the elements affecting the climate of India?
Ans. The elements affecting the climate are temperature, atmospheric pressure, wind, humidity and precipitation.

(ii) Why does India have a monsoon type of climate?
Ans. India is defined as a climatic region with monsoon climate. It is strongly governed by the monsoon winds.

(iii) Which part of India experiences the highest diurnal range of temperature and why?
Ans. The Thar Desert has a wide difference between day and night temperatures. There is no sea around to moderate the range of variation of temperatures during day and night.

(iv) Which winds account for rainfall along the Malabar Coast?
Ans. Malabar Coast gets rains from depressions and cyclones.

(v) What are jet streams and how do they affect the climate of India?
Ans. Jet streams are high velocity westerly winds blowing through a narrow zone in the upper troposphere. The westerly flows are responsible for the western disturbances experienced in the north and north-western parts of the country. The easterly jet streams cause tropical depressions during the monsoon as well as October-November months.

(vi) Define monsoons. What do you understand by “break” in monsoon?
Ans. Monsoon refers to the seasonal reversal in the wind direction. Monsoon ‘break’ refers to the happening of wet and dry spells during the rainy season. The monsoon rains take place only for a few days at a time. They are interspread with rainless
intervals.

(vii) Why is the monsoon considered a unifying bond?
Ans. Monsoons are uncertain but all the same they act as a unifying force on the climatic unity of India. July and August are wet almost all over the country. In spite of their vagaries, the monsoons have a very important place in the cultural life of the people. There is so much poetry and music that centres round the rains. All over northern parts of India, there are festivals like Varsha Mangal and special songs for the seasons. For the farmers, the rains bring prosperity. The Indian landscape, its fauna and flora, its agriculture all revolve round the monsoon phenomenon. The arrival of rains is eagerly awaited.

Question.3. Why does rainfall decrease from east to the west in Northern India?
Ans. June onwards, there is continued low pressure over the north-west region. This attracts trade winds from the Indian Ocean. The winds are trapped by air circulation over India. These winds are loaded with abundant water vapours. The winds blow at a very fast speed. The hilly ranges of the northeast account for heavy rainfall in the region. As these winds travel westwards the amount of moisture contained goes on depleting. There is as such a decrease in rainfall from east to west in northern India.

Question.4. Give reasons as to why :
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent.
Ans. With the reversal in the direction of the surface winds, the monsoons withdraw from the Northern Plains. This reversal occurs as the monsoon trough becomes weaker with the approach of winter months.

(ii) The bulk of rainfall in India is concentrated over a few months.
Ans. The bulk of rainfall is concentrated over the months of June-September. As winter approaches, there is a reversal in the direction of surface winds and monsoons withdraw from the Northern Plains.

(iii) The Tamil Nadu coast receives winter rainfall.
Ans. Winter rains in Tamil Nadu are caused by north-east trade winds (also known as north-east monsoons). That is the only part of India that gets rains during the winter months.

(iv) The delta region of the eastern coast is frequently struck by cyclones.
Ans. With the onset of winter season, there is a shift in low pressure conditions from the northwestern plains to the Bay of Bengal. During the middle of November, this shift results in the occurrence of cyclones. The deltas of Krishna and Kaveri rivers (and also Bangladesh) have to bear the fury of these cyclones year after year.

(v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.
Ans. Rainfall in India is influenced by location as well as relief features. Areas situated in the direction of the monsoon winds receive more rainfall. The rainfall goes on decreasing from east to west. The moisture content of the monsoons goes on decreasing as they move westward. Areas situated in extreme west and devoid of hilly ranges that intercept the monsoon remain
drought prone.

Question.5. Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Ans. There are wide variations in climatic conditions over different parts of the country. Most parts of the country have dry winters. The Coromandel coastal areas are an exception.
Winters are severe in the north. The temperature increases from north to south. As the Northern Plains shiver with 10-15 degrees Celsius temperature, Chennai has temperature around 25 degree Celsius. Higher slopes of the Himalayas experience snowfall. The peninsular region does not have a well defined cold season. Nearness to the sea ensures that there are no wide variations due to seasonal changes.
Rainfall may go up to 1080 mm in the Khasi hills. Rajasthan and parts of Gujarat remain prone to droughts. During the summer seasons temperatures go up to 48 oC in the western parts of India. May is the season of loo. These hot and dry winds cause intense heat. Temperature variations (June-December) are minimal at places like Leh. Places in the Northern Plains experience severe heat in the summers and extreme cold weather during the winter months.

Question.6. Discuss the mechanism of monsoons.
Ans. The north-east trade winds that blow during the winter months get replaced as the summer season sets in. There is continued low pressure over the north-west region. This attracts trade winds from the Southern Hemisphere. Coming from the Indian Ocean, these winds cross over the Bay of Bengal and the Arabian Sea. They are then trapped by air circulation taking place over India. These winds are loaded with moisture and blow at a very fast speed. The rain caused by south-west monsoon is not uniform. The areas of Western Ghats situated in the direction of the winds get more rainfall than the other side. The cyclonic depressions formed at the head of the Bay of Bengal cause uneven and uncertain distribution of rainfall. These depressions move towards the low pressure monsoon trough which is not steadily placed. For a variety of reasons, they move northwards or southwards. When the axis of the trough moves close to the Himalayas, there are heavy rains in the Himalayan regions. The plains get dry spells. With the approach of winter, the monsoon trough becomes weaker. There is reversal in the direction of surface winds with the approach of winter. The monsoons now withdraw from the Northern Plains. The shift in the low pressure conditions from north-western plains to the Bay of Bengal causes cyclones and rains in the Coromandel Coast.

Question.7. Give an account of weather conditions and characteristics of the cold season.
Ans. The winter season lasts from the month of December to February. The season is mostly dry. Cold is severe in the northern parts of the country. The southern parts have only mild cold. In the Northern Plains the days may be generally warm but the nights are cold. Places situated at high altitudes have snowfall.
Light rainfall may occur during the winter months caused by western disturbances. These disturbances are caused by shallow cyclonic depressions originating over the east Mediterranean Sea. Travelling eastward, these depressions reach the north-western parts of India. On their way these get loaded with moisture from the Caspian Sea and the Persian Gulf.
The western disturbances are responsible for snowfall in the western Himalayan regions apart from light rains over north-western parts of the country. Winter rains are often followed by cold waves. Tamil Nadu gets rains in winter by the northeast trade winds.

Question.8. Give the characteristics and effects of the monsoon rainfall in India.
Ans. The monsoon rainfall in India is not evenly distributed. Rainy season has a longer spell in the eastern parts of the country. The northwest gets rains for barely two months. The duration of the rainy season is longer in the south than in the north.
The southwest monsoon pours more water over areas of Western Ghats that are situated in the direction of the winds. The quantity of rainfall is heavy in the hilly regions of the north-east. It keeps declining as the winds move westwards. Patna gets more rain than Allahabad. Similarly, Delhi gets much less rain than Kolkata.
Monsoons are not steady. Rainy days are interspersed with rainless days. When the rains are heavy, the rivers get flooded causing heavy damage in the plains year after year. A dry spell would cause as much misery as the river floods. The arrival and departure
of monsoons is uncertain. So is the extent of rainfall in any given rainy season. These characteristics of monsoon has a very destabilising effect on Indian economy that continues to be predominantly agricultural and severely dependent on rainfed irrigation.

Map Skills

Question.1. On an outline map of India, show the following.
(i) Areas receiving rainfall over 400 cm.
(ii) Areas receiving less than 20 cm of rainfall.
(iii) The direction of the southwest monsoon over India.
Answer.map-skills-ncert-geo-09-chapter-4

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