Class 9 NCERT Geography Climate Extra Questions

Climate: Class 9 Extra CBSE Questions: The chapter explains different factors that affect the climate of a country. Latitude. altitude, distance from the sea and wind and pressure belts affect the climate of a country. The climate of India is Monsoon type which is affected by many factors when we talk about onset and advancement of monsoon in India. Here are given some extra questions for revision.


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Climate: Class 9 Geography Extra Questions


Q. “There is great variation in the amount and type of precipitation in India.” Justify the statement. [CBSE 2015, 11]

Answer

The great regional variations in the climatic conditions of India are seen mainly in temperature and rainfall.

Temperature: In summer the temperature rises above 50° Cin some parts of Rajasthan while in Jammu and Kashmir it may be around 20° C at the same time. During winter the temperature goes down to even minus 45° C while it may be around 22° C in the Thiruvananthapuram. Coastal areas have a moderate climate while the interior of India has extreme or continental climate.

Precipitation: The rainfall is as high as 400cm in in Meghalaya while it is less than 10 cm in W. Rajasthan and Ladakh. Most part of India gets rainfall between June to September while Tamil Nadu receives rainfall between November and December.

Q. Describe the western cyclonic disturbance and its impact on climate. [CBSE 2015]

Ans. The western cyclonic disturbances are weather phenomena of the winter months brought in by the westerly flow from the Mediterranean region. They usually influence the weather of the north and north-western regions of India. Tropical cyclones occur during the monsoon as well as in October- November, and are part of the easterly flow. These disturbances affect the coastal regions of the country.

Q. What is the role of ‘western disturbances’ in the Indian climate? [2015]

Answer:

(i) A characteristic feature of the cold weather season over the northern plains is the inflow of cyclonic disturbances from the west and the northwest.

(ii) These low pressure systems originate over the Mediterranean Sea and Western Asia and move into India, along with easterly flow.

(iii) They cause the much-needed winter rains over the plains and snowfall in the mountains.

(iv) Although the total amount of winter rainfall, locally known as ‘Mahawat’ is small, it is very useful for rabi crops. These winds are called western disturbances since they came from the western part of India.

Q. What are jet streams and how do they affect the climate of India? [2012, 11]

Ans. 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/hr. in summer to about 184 km/hr. in winter. These jet streams are located approximately over 27°–30° north latitude. Therefore, they are known as sub-tropical westerly jet streams.

Over India, these jet streams blow south of the Himalayas, all through the year except in summer. The western cyclonic disturbances experienced in the north and north-western parts of the country are brought in by this westerly flow.

In summer, the sub-tropical westerly jet stream moves north of the Himalayas with the apparent movement of the sun. An easterly jet stream, called the sub-tropical easterly jet stream blows over peninsular India, approximately over 14°N during the summer months.

The westerly flows are responsible for the western disturbances experienced in the north and north–west parts of India. The easterly jet streams cause tropical depressions during the monsoon as well as during the months of October–November.

Q. What are the six major controls of the climate of the world? [2012]

Ans. The six major factors controlling climate are given below.

(i) Latitude: Due to the round shape of the Earth, the amount of solar energy received varies according to latitude. As a result, air temperature decreases from the equator towards the poles.

(ii) Altitude: As one moves up to the higher altitudes, the atmosphere becomes less dense and temperature decreases. Therefore, hills are the cooler during summers.

(iii) Pressure and winds: Pressure and wind system of an area depend on the latitude and altitude of the place. Thus, it influences the temperature and rainfall pattern.

(iv) Distance from the sea: If the region is close to the sea, it makes the temperature moderate but if it is away from the sea, it experiences extreme weather conditions.

(v) Ocean currents: Ocean currents along with the onshore winds affect the climate of a coastal area. Any coastal area with warm or cold currents flowing fast, it will become warm or cold if the winds are onshore.

(vi) Relief: High mountains act as barriers for cold and hot winds. They may also cause precipitation if they lie in the path of rain-bearing winds. The leeward side of mountains remains dry, whereas the windward side is able to receive rain

Q. 2. Explain any three factors controlling the Indian weather conditions. [2013]

Ans. The Climate and associated weather conditions in India are governed by the following Atmospheric conditions:

(i) Pressure and Surface Winds: Pressure and surface wind conditions in India are unique. During winters, there is high pressure area in North of the Himalayas. In summers, a low-pressure area develops over interior Asia as well as over North-western India.

(ii) Upper Air Circulation: The Upper Air Circulation in the oceans are dominated by westerly flow. An important component of this flow is Jet Streams.

(iii) Western Cyclonic Disturbances: The Western Cyclonic Disturbances experienced in the North and North western parts of the country are brought in by the westerly flow.

Q. State how the pressure and wind conditions over India are unique.

Answer:

  • During winter, a high pressure area develops in north of the Himalayas.
  • Cold dry winds blow from this region to the low pressure areas over the oceans to the south.
  • 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.
  • Air moves from the high pressure area over the southern Indian ocean in a south-westerly direction, crosses the equator and turns right towards the low pressure area over the Indian sub-continent.
  • These winds are known as south-west monsoon winds.
  • These winds blow over the warm oceans, gather moisture and bring widespread rainfall over the mainland of India.

Q. 6. Discuss the mechanism of monsoons. [2012, 11]

Ans. Following are the factors responsible for the mechanism of monsoons:

  • 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.
  • The Inter Tropical Convergence Zone (ITCZ) is normally positioned about 5°N of the equator. During summer, it shifts over the Ganga plains. It is also known as the monsoon trough during the monsoon season.
  • The high pressure area, east of Madagascar is approximately 20°S over the Indian Ocean. This area affects the Indian Monsoon.
  • The Tibetan plateau gets intensely heated during summer. This leads in strong vertical air currents and formation of high pressure over the plateau. This high pressure zone is about 9 km above the sea level.
  • The westerly jet stream moves to the north of the Himalayas, and the tropical easterly jet stream moves over the Indian Peninsula during summer.
  • The periodic change in pressure conditions between Pacific Ocean and the Indian Ocean, also known as the ‘Southern Oscillation’ or ‘SO’ also affects the monsoon.
  • The difference in pressure over Tahiti and Darwin is computed to predict the intensity of the monsoons. Tahiti (18°S/149°W) lies in the Pacific Ocean and Darwin (12°30’S/131°E) lies in northern Australia. If the pressure differences are negative, it means a below average and late monsoon. 

Q. 8. Give a brief account of how monsoons advance into India.

Answer:

(i) In early June, the low pressure conditions over the northern plains intensify.

(ii) These south-east trade winds cross the equator and blow in south-westerly direction, entering the Indian peninsula as the south-west monsoons.

(iii) As these winds blow over warm oceans, they bring abundant moisture to the sub-continent.

(iv) These winds are strong and blow at an average velocity of 30 km per hour.

(v) Early in the season, the windward side of the Western Ghats receives very heavy rainfall, more than 250 cm.

(vi) The maximum rainfall of this season is received in the north-eastern part of the country. Mawsynram in Khasi Hills receives the highest average rainfall in the world.

(vii) Rainfall in the Ganges valley decreases from east to the west Rajasthan and parts of Gujarat get scanty rainfall. 

Q. Give a brief account of the condition and characteristics of the retreating monsoons.

Answer:

  • This is the transition period during the months of October and November.
  • With the apparent movement of the Sun towards the south, the low pressure trough over the northern plains becomes weaker. This is gradually replaced by a high pressure system.
  • The south-west monsoon winds weaken and start withdrawing gradually.
  • By the beginning of October, the monsoon withdraws from the northern plains.
  • The months of October and November form a period of transition from hot rainy season to dry winter conditions.
  • When monsoons retreat, skies get clear and the temperature rises.
  • While day temperatures are high, nights are cool and pleasant. The land is still moist.
  • Owing to the conditions of high temperature and humidity, the weather becomes oppressive during the day. This is commonly known as October Heat.
  • The low pressure conditions get transferred to the Bay of Bengal by early November.
  • The cyclonic depressions originate from the Andaman Sea and cause heavy and widespread rains on the eastern coast.
  • These tropical cyclones are often very destructive and affect the coast of Odisha, West Bengal and Bangladesh.

Q. How does the process of withdrawal of monsoon take place in India?

Answer:

(i) Withdrawal or the retreat of monsoon is a more gradual process.

(ii) The withdrawal of the monsoon begins in the north-western states of India, by early September.

(iii) By mid-October, it withdraws completely from the northern half of the peninsula.

(iv) The withdrawal from the southern half of the peninsula is fairly rapid.

(v) By early December, the monsoon withdraws from the rest of the country.

Q. 2. Describe the climatic conditions of India during Retreating Monsoon. [2012]

Ans. Climatic conditions during Retreating Monsoons are:

(i) This is the transition period during the months of October and November.

(ii) The season changes from hot and rainy to dry winter conditions. The retreat of the monsoon is marked by clear skies and rise in temperature. Day temperatures are high and nights are cool and pleasant.

(iii) Low–pressure conditions get transferred to the Bay of Bengal by early November.

(iv) Cyclonic depressions in the Andaman Sea cause heavy rainfall and are destructive tropical cyclones.

Q. What do you understand by the phenomenon of ENSO?

Answer:

(i) Normally, when the tropical eastern south Pacific Ocean experiences high pressure, the tropical eastern Indian Ocean experiences low pressure.

(ii) But in certain years, there is a reversal in the pressure conditions and the eastern pacific has low pressure in comparison to the Indian Ocean.

(iii) This periodic change in pressure conditions is known as Southern Oscillation (SO).

(iv) The difference in pressure over Tahiti, in the Pacific Ocean and Darwin in northern Australia is computed to predict the intensity of the monsoon.

(v) A feature connected with the SO is the El Nino, a warm ocean current that flows past the Peruvian coast, in place of the cold Peruvian current every 2 to 5 years.

(vi) The changes in pressure conditions are connected to the El Nino. Hence, the phenomenon is referred to as ENSO (EI Nino Southern Oscillations).

Q. Give reasons why parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought prone. [2011]

Answer:

(i) Western Rajasthan and part of Gujarat are desert type regions with extreme climate. Intense thermal heating makes the desert land very dry.

(ii) The Arabian Sea branch runs parallel to Aravallis, providing no barriers to the clouds, leaving it again a dry region.

(iii) The Bay of Bengal branch is unable to reach up to western part and in winters even western disturbances also hardly give any rains to this region.

(iv) The leeward side of the Western Ghats also lies in the rain shadow of South West monsoon.

(v) With the result, regions lying at the same latitude are unable to receive rains, if they are on the leeward side of the Western Ghats.

Q. How is the Arabian Sea branch of South-west Monsoons responsible for good rainfall in the Northern Plains of India? Why doesn’t it give rain in the Central Peninsula? [2011]

Ans. (i) The part of South-west monsoons which blow over the Arabian Sea is responsible for high rainfall on the western coast of India.

(ii) These winds enter through Saurashtra and enter the Northern plains. These winds strike the Himalayas and give fairly good rainfall and abandon moisture.

(iii) South-west monsoons are perpendicular to the direction of the Western Ghats thus; they give heavy rainfall on the windward side of the Western Ghats.

(iv) Central Peninsula lies on the leeward side of the
Western Ghats. This Arabian Sea branch of Southwest Monsoon does not reach the region

Q. Indian Monsoon is highly unpredictable? Do you agree with this statement? Give reasons in support of your answer. [2014, 2013]

Ans. Yes, the monsoon is known for its uncertainties and this unpredictability has great impact agriculture and thus the economy.

(i) The alternation of dry and wet spells varies in intensity, frequency and duration.

(ii) It may cause heavy floods in one part and drought in the other part.

(iii) It is often irregular in its arrival and retreat.

Q. “Rainfall is unevenly distributed in India.” Justify in five points. [2011]

Answer:

(i) Monsoon rains are confined only to few months of a year.

(ii) The Topography of India leads to more rainfall in some regions while less in others.

(iii) Cyclones help rain in scattering at places, while other places remain without rain.

(iv) Whole of India does not receive rain by Monsoon winds. Eastern Coast of India gets rain only from North–east monsoons during the month of December–January

Q. 4. Highlight the characteristics of cold weather season in India. [2012]

Ans. Characteristics of cold weather season in India are:

  • The winter season begins from mid-November and continues till February; in northern India.
  • December and January are the coldest months in the northern part of India.
  • The temperature ranges between 10°-15°C in the northern plains, while it ranges between 24°-25°C in Chennai.
  • Days are warm and nights are cold.
  • Frost is common in the north and the higher slopes of the Himalayas experience snowfall.
  • The northeast trade winds prevail over the country in this season. As these winds blow from land to sea, most parts of the country experience a dry season.
  • The weather is usually marked by clear sky, low temperatures and low humidity and weak variable winds.
  • The inflow of the cyclonic disturbances from the west and the northwest is a characteristic feature of the cold weather over the northern plains.
  • These low-pressure systems originate over the Mediterranean Sea and Western Asia and move into India. They cause winter rains over the plains and snowfall in the mountains.
  • The winter rainfall is in small amount but is very important for the rabi crop. This rainfall is locally known as mahawat.
  • The peninsular region does not have a well-defined cold season due to the moderating influence of the sea. 

Q. Describe any five characteristic features of the Hot Weather Season in India. [2015]

Answer:

(i) Hot seasons lasts from March to May.

(ii) Low pressure develops extending from Thar Desert, in the North–west to Patna and Chota Nagpur Plateau in the East and South–east.

(iii) Temperature ranges between 38° C to 45° C in the North.

(iv) Pre–monsoon showers are common; are known as Kal Baisakhi, Mango Showers.

(v) Striking feature: Loo, a hot, dry, dusty and strong wind blows over the North and North-west India, dust storms. 

Q. Differentiate between the Cold Weather Season and the Hot Weather Season of India by explaining two distinctive features of each. [2011]

Ans. Cold Weather Season:

  • It begins from mid-November in northern India and stays till February.
  • The temperature decreases from South to North.
  • Days are warm and nights are cold.

Hot Weather Season:

  • It begins from March and stays till May.
  • Experiences rising temperature and falling air pressure in North India.
  • Hot and dry wind called ‘Loo’ blows during the day.

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