1. Explain any three factors controlling the Indian climatic conditions.
(i) The location and relief features
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(ii) Pressure and surface winds
(iii) Upper air circulation what are ‘Jet Streams’ and how do they affect the climate of India?
2. What are Jet streams and how do they affect the climate of India?
Jet Stream:
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Fast blowing air currents moving in a narrow zone of the atmosphere. They help in bringing the western disturbances to north and north-western parts of India.
(i) It brings winter rains over north and north-western parts of India.
(ii) It is important for Rabi crops. .
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3. Why do the Western Ghats receive more rainfall than the Eastern Ghats?
Explain briefly.
(i) Western Ghats receive rainfall from the Arabian Sea monsoon winds.
(ii) Do not allow these winds to cross over without shedding their moisture on the western slopes.
(iii) A part of these winds that reach the Eastern Ghats is almost dry. Study the climate data of the given place and answer the following questions:
5. Describe the main features of Retreating monsoon season of India.
(i) Main months – Oct and Nov.
(ii) The monsoons trough becomes weaker and is replaced by high pressure system, monsoons withdraw gradually.
(iii) Clear skies and rise in temperature, the weather becomes oppressive, known as October heat.
6. Describe any three facts which affect the mechanism of monsoon.
(i) The differential heating and cooling of land and water
(ii) The shift of the position of Inter Tropical convergence zone in summer
(iii) The presence of H.P. area, east of Madagascar
(iv) The Tibetan plateau gets intensely heated.
(v) The movement of the westerly jet stream to the north of the Himalayas, presence of the tropical easterly jet stream over Indian Peninsula.
7. Why does Mumbai receive more rainfall in summer while Chennai receives rainfall in winter?
(i) Mumbai receives more rainfall in summer from Arabian Sea branch from June to September.
(ii) Located on the western coast.
(iii) Located on the windward side of Western Ghats. Chennai is located o the eastern coast
(i) Arabian Sea branch becomes off shore.
(ii) Bay of Bengal branch moves parallel; to the eastern coast.
(iii) Chennai receives rain from north-east monsoons and by cyclone in October to December.
8. How do monsoon act as a unifying bond for India. Explain.
Monsoons act as a unifying bond:
(i) The Indian landscape, its animal and plant life, its entire agriculture calendar and the life of the people, including their festivities, revolve around this phenomenon.
(ii) Year after year people of India from north to south and from east to west, eagerly await the arrival of the monsoon.
(iii) These monsoon winds bind the whole country by providing water to set the agriculture activities in motion.
(iv) The river valleys which carry this water also unite as a single river valley unit.
9. Define monsoon. Differentiate between ‘Burst of monsoon’ and ‘Break of the monsoon’. Monsoon s Monsoon refers to the seasonal reversal in the wind direction during a year.
Burst of the Monsoon:
Rainfall increases suddenly and continues constantly for several days. Break of the Monsoon: Monsoon rains take place for a few days only. Rainless intervals.
11. Explain the importance of monsoon rainfall in India.
India would have been an arid land or desert if there had been no phenomena of monsoons because:
(i) India receives 75% to 90% rainfall. ‘
(ii) Himalayas don’t allow south – west monsoons to cross over to Tibet.
(iii) The peninsular shape sub-divides the S.W. monsoons.
14. What are Western disturbances? How do they affect the climate of India?
Western disturbances are the temperate cyclones which originate over Mediterranean Sea and Western Asia and move into India, along with the westerly glow of jet streams.
(i) They disturb the calm and quite weather of north and north western India by causing cyclonic rains over the plains and snowfall in the mountains.
(ii) Winter rainfall caused by them locally known as ‘Mahawat’ is of immense importance for the cultivation of Rabi crops.
15. Describe the mechanism of monsoon.
Mechanism of monsoons:
(i) Differential heating and cooling of land and water
(ii) The shift of ITCZ in summers to Ganga Plain
(iii) High pressure east of Madagascar
(iv)Intense heating of Tibetan Plateau in summers
16. Describe the cold weather season of India.
Account of cold weather season:
(i) Duration: December, January, February.
(ii) High pressure area prevails over North. West India.
(iii) North East trade winds blow over India.
(iv) The temperature from South to North.
(v) Western Cyclonic Disturbance, {any three)
17. What are Jet Streams? How is jet stream related with Western Cyclonic Disturbances?
Jet streams are a narrow belt of high altitude westerly winds in the troposphere. Their speed varies from about 110 km/Hr in summer to about 184 km/Hr in winter.
(i) Little amount of winter rains over the plains and snowfall in the mountains as an impact of western cyclonic disturbances from the Mediterranean Sea.
(ii) They have immense importance for the cultivation of Rabi crops in North India.
18. Explain three striking features of hot weather season.
Three striking features of hot weather seasons are:
(i) Hot and dry wind blow called ‘loo’.
(ii) Dust storms lower the temperature.
(iii) Localized thunders storms, torrential downpours.
(iv) Pre-monsoon showers. (Any three)
19. What are the elements of weather and climate? Distinguish between weather and climate.
The elements of weather and climate are temperature, atmospheric pressure, wind, humidity and precipitation.
Weather: refers to the state of the atmosphere over an area at any point of time.
Climate:
It refers to the sum total of weather conditions and variations over a large area for a long period of time, (more than 30 years).
21. Why the distribution of rainfall in India is uneven? Give any three reasons.
(i) Hilly and forest areas get heavy rainfall because of high altitude and abundance of trees
(ii) On the other hand, those areas which have no mountains to check the rain bearing winds get scanty rainfall. Example: Aravalli hills standing parallel to the monsoon.
(iii) Area which comes in the rain shadow, like eastern side of the Western Ghats or ladakh, does not get much rainfall.
(iv) Rain – bearing winds get more rainfall as compared to areas which come last of all. (Any three)
22. What influence has the Himalayas on India’s climate?
(i) The lofty mountains have provided India with a compact physical setting.
(ii) They protect the sub-continent from the northern winds. These cold and chilly winds originate near the Arctic Circle and blow across central and eastern Asia.
(iii) The mountain wall blocks the monsoon winds and causes them to shed bulk of their moisture in India.
23. Explain the mechanisms responsible for the occurrence of the monsoons over the Indian sub-continent.
Mechanisms are:
(i) Differential heating and cooling of land and water.
(ii) Shifting of the Inter Tropical Convergence Zone.
(iii) Presence of high pressure area, east of Madagascar.
(iv) Heating of the Tibetan Plateau.
(v) Movement of westerly Jet stream, north of the Himalayas and tropical easterly Jet stream over the Indian Peninsula
25. What is meant by the term ‘Monsoon’? Give the main characteristics of the monsoon.
Monsoon:
Monsoon is derived from the Arabic word mausim which means season.
Characteristics:
(i) It is associated with the seasonal reversal in the wind direction during the year.
(ii) The monsoon winds are pulsating in nature.
(iii) It is associated with an increase of rainfall which continues for several days-the burst of the monsoon.
(iv) It also has breaks in rainfall. It has wet and dry spells related to the monsoon trough, (any two)
26. What is the difference between weather and climate? Name the type of climate of India and why?
(A) Weather refers to the state of the atmosphere over an area at any point in time.
Climate refers to the sum total of weather conditions and variations over a large area for a long period of time.
(B) India has a monsoon type of climate. India lies in South Asia where the monsoon winds prevail.