Thursday, 24 December 2015

Chapter 4 CLIMATE | Geography | CBSE Class 9th | Solved Exercises

Facts About India:
  • Climate of India: Tropical Monsoon type.
  • Highest temperature: Barmer (Rajasthan) 500 C.
  • Lowest temperature: Kargil (Ladakh) 550 C.
  • Rainiest place: Mawsynram- 140 cms annual rainfal.
  • Indian ocean: Storeshouse of moisture for Monsoons.
  • The Himalayas: A climatic divide.
  • Monsoon: Derived from Arabic word 'Mausim'.
  • Seasons in India: Cold, Hot, Rainy and Retreating Monsoons.
  • Western Disturbances: Cyclones from Mediterranean Sea. Give rainfall in N.w India in winter.
  • South-West Monsoons: 1st - Date of onset in Kerala. Arabian sea Branch and Bay of Bengal.
  • Rain Shadow Areas: Deccan Plateau, N.W. Kashmir, Shillong Plateau
  • North-East Monsoons: Retreating Monsoons (October-November) Give rainfall on the Eastern coast.


Question 1. Choose the right answer from the four alternative given below:

(i) Which one of the following places receives the highest rainfall in the world?

(a) Silchar
(b) Mawsynram
(c) Cherrapunji
(d) Guwahati

Answer : (b) Mawsynram

(ii) The wind blowing in the northern plains in summers is known as:

(a) Kaal Baisakhi
(b) Loo
(c) Trade Winds
(d) None of the above

Answer : (b) Loo

(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) Southwest monsoon

Answer : (c) Western disturbances

(iv) Monsoon arrives in India approximately in:

(a) Early May
(b) Early July
(c) Early June
(d) Early August

Answer : (c) Early June

(v) Which one of the following characterizes the cold weather season in India?

Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights

Answer : (c) Cool days and cold nights

Question 2. Answer the following questions briefly.

Question (i). What are the controls affecting the climate of India?

Answer : India's climate is affected by latitude, altitude, pressure and winds, distance from the sea, ocean current and physiography.

(ii). Why does India have a monsoon type of climate?

Answer : India has Monsoon type of climate because:
  • It is strongly governed by a Monsoon winds.
  • Pre-Monsoon, Monsoon and post Monsoon duration is called here seasons.
  • India exits in tropical area (viz. half of it is lying at south to the Tropic of Cancer between 200N and 200S).
  • Here are atmospheric conditions of pressure and surface winds, upper air circulation and westren disturbances and tropical cyclones.
  • Here is an active Coriolis force, that deflects winds towards the right in the Northern Hemisphere and left in the Southern Hemisphere.
  • Here acts the ENSO (El Nino Southern Oscillations).

(iii). Which part of India does experience the highest diurnal range of temperature and why?

Answer : These are the north-western parts ( Haryana, Punjab, U.P, Delhi etc.) of India where temperature rises up to 480 Celsius. This is because:
  • Low pressure conditions intensifies in north-western parts of India during May-June.
  • The south-west monsoon enters in peninsular India and Its humidity increases  in its north-Western parts.
  • Hot dry winds namely Loo, starts blowing and dust storms spurt as south-westerly winds blow violently to compensate the low pressure conditions formed in north-western parts of the country.

(iv). Which winds account for rainfall along the Malabar coast?

Answer : Mumbai lies on the western coast, facing Western Ghats. The Arabian Sea branches of Monsoon are on-shore moist laden winds and give heavy rainfall on the western slopes Of Western Ghats and the western coast, But Pune lies on the eastern slopes of western Ghats. it lies in the rain shadow of Western Ghats. Monsoon after descending down Western Ghats become dry and give less rainfall at Pune.

(v). What are Jet streams and how do they affect the climate of India?

Answer : These are fast blowing winds of steady velocity, moving in a narrow zone of the upper atmosphere. They are called jet streams. The southern branch of the westerly jet stream blows in an eastward direction south of the Himalayas. it exercises an important influence on the winter weather in India. During the summer season, the easterly jet stream flows over northern India along 250N. it helps distributing the Monsoon rainfall over the whole of India.

(vi). Define monsoons. What do you understand by “break” in monsoon?

Answer : Monsoon are generally rain bearing and directing winds. This term has been derived from the Arabic word "mausim" first used by the Arab traders who used to come India for trading through sea routes. It means season. We, therefore, can state them seasonal reversal of the wind system in Monsoon.
Breaking Monsoon:
Rain taking place only for a few days at a time is called "Break Monsoon". In brief, the intermissions amid raining is break Monsoon . it is related to the movement of the Monsoon through.

(vii). Why is the monsoon considered a unifying bond?

Answer : The term implies "unifying bond" an attachment or affection of something with another. Such conditions as formed when we talk of Monsoon's attachment with India. The cold winds from north side do not strike India as there exists a natural barrier of the Himalayas. In other places except India, are covered with the extreme cold wind in the same latitude. Similarly, the peninsular India's covered by the seas from three sides. This arrangement also ensures a moderate temperature in India. Again the seasonal reversal of wind system provides a rhythmic cycle of seasons. India folk songs, folk lore,  stories, manner of dress and diet etc. are added to the Monsoon. Hence we can state the Monsoon in India acts as an unifying bond.

Question 3. Why does the rainfall decrease from the east to the west in Northern India.
Answer : This is because:
  • The Bay of Bengal branch of Monsoon is deflected after its reach at Assam and it therefore, rains over the Ganga plains.
  • The Arabian sea branch of the Bay of Bengal branch both rain simultaneously in the westren part of Northern India and not north India.
  • Thus both the branches of Monsoon are depleted water and the rain gradually decreases towrds north side. Rajasthan and parts of Gujarat receive scanty rainfall.

Question 4. Give reasons as to why.

Question (i). Seasonal reversal of wind direction takes place over the Indian subcontinent?

Answer : This caused of wins reversal in Indian subcontinent are:

  • Intensive heating during summer over northern plains cause the heat low around the Arabian sea.
  • Monsoon trough is found at I.T.C.Z. normally positioned about 500N of the equator.
  • Formation of high pressure are at 200S over the Indian ocean.
  • Strong vertical area and high pressure due to immense heat over the Tibetan plateau.
  • Movement of westerly jet to north of the Himalayas and the tropical easterly jet over the Indian peninsula.

(ii). The bulk of rainfall in India is concentrated over a few months.

Answer : During the four month i.e, of June to September, the south west Monsoons flow northwards in two branches:
  • Arabian sea branch and
  • Bay of Bengal
Both of these branches do rain in India peninsula till the low pressure is existed. However, the withdraw of Monsoon begins in the western parts of north western states of India by early September. Rain is concentrated for four months only because of the Inter Tropical Convergence Zone ( a broad through of low pressure) in equatorial latitudes. Second reason for this is pressure over Tahiti (Pacific Ocean) and Drawing (North Australia) over India ocean is computed to predict the intensity of the Monsoons. El Nina, a warm ocean current (that replaces cold current in 2-5 years.) in Peru coast is also responsible for the short concentration of rainfall in India.

(iii). The Tamil Nadu coast receives winter rainfall.

Answer : The North-East Monsoon start blowing in October month from the land (i.e. north-eastern parts of India) to the sea. These bear no water til their access at the Bay of Bengal. However, they get some moisture from sea here and cause rain in the coast of Tamil Nadu.

(iv). The delta region of the eastern coast is frequently struck by cyclones.

Answer : Low pressure conditions are formed during October and November every years on the Bay of Bengal. Owing to this shift transfer of pressure, cyclonic depression is formed in the Andaman sea. These are called tropical cyclones and spread devastation in eastern deltas.

(V). Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.

Answer : This happens due to collision of rain bearing Arabian branch of Monsoon against the high elevated Western Ghats and depletion of water there. Again the Aravali Hills beng not much elevated, the Monsoon winds pass from there untrained.

Question 5. Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Answer : Due to vast size of India, many regional variations in climatic conditions are found But due to the influence of Monsoons, India has a broad unity of Monsoon type of climate having same rhythm of season. Many factors like location, altitude, distance from the sea, general relief produce regional variations in pattern of winds, temperature and Rainfall. The following examples illustrate the climatic differences:
  • Temperature. Barmer (Rajasthan) has recorded day temperature of 500c in summer, while Hilly regions like Gulmarg (Kaashmir) have a day temperature 220C in June. The winter temperature at Dras and Kargil (Leh) fall as low as- 450C, on the other hand Chennai may record only 200C in December. The annual range of temperature is about 120C at Cochin while it is about uniform temperatures throughout the year.
  • Rainfall. Striking differences are found in Rainfall pattern. Mawsynram (Meghalya) with a annual rainfall of 1140 cms. is the rainiest place in the world while Jaisalmer (Rajasthan) rarely get more than 20 cms. of annual rainfall. The East coastal plain get rain-storms while Coromandel coast remains dry. when Brahmputra valley is submerged with floods, it is drought in Bihar.
  • Monsoons.The dates of onset and withdrawal of Monsoons differ in various parts. The western coast gets Monsoons in the first week of June while the interior parts like Punjab have Monsoon by the first week of July.
  • Seasons. The southern parts of the country have uniformly high temperatures throughout the year. There is no water season in the south. On the other hand seasonal extremes are found in north. 'Loo' produces a heat wave in summer while cold was is felt in winter

Question 6. Discuss the mechanism of monsoons.
Answer : To discuss the mechanism of Monsoon and understand it, the meteorological date has been taken from the Indian- ocean region as well as from the other areasof the world. Certain factors as taken to be the cause of wind reversal. They are:
  • The heat low around the Arabian sea caused due to intensive heating during the Pre-Monsoon months.
  • The northern most position of the Inter-Tropical Convergence Zone (ITCZ) in summer over the Ganga plain. This is the equatorial trough normally positioned about 50N of the equator, also known as the Monsoon.
  • The presence of high pressure area, east of Madagascar approximately at 200s over the Indian ocean. The intensity and position of the high pressure area affects the Indian Monsoon.
  • The Tibetan high level plateau gets intensely heat during summer which result in strong vertical currents and formation of high pressure over the plateau at about a kilometer above the sea level.
  • The movement of the westerly jet to the north of the Himalayas and the presence of the tropical easterly jet over the Indian Peninsular during summer.
Apart from this, it has also been noticed that changes in the pressure conditions over the southern oceans also affect the Monsoons.

Question 7. Give an account of weather conditions and characteristics of the cold season
Answer : Weather conditions in the winter are:
  • The cold weather season begins from mid-November in northern India and stays till February. December and January are the coldest months. The temperature decreases from south to north. The average temperature on the eastern coast is between 240- 250C, while in the Northern Plains ir ranges from 100- 150C. Days are warm and nights are cold. Frost is common in the north and higher slopes of the Himalayas experience rainfall.
  • During this season, the north-east trade winds blow over the country. The blow from land to sea, so for most part of the country it is a dry season. some rainfall occurs on the Tamil nadu coast from these winds as here they blow from sea to land.
  • In the northern part of the country, a feeble high pressure region develops with light winds. They blow from the Ganga valley and the north- west. The weather is fine, marked by clear sky, low temperature, low humidity and feeble variable winds.
A characteristics feature of the cold weather season over the northern plains is the inflow of depression from the west and northwest. These low pressure systems, called the Western Disturbance, originate over the Mediterranean sea and West Asia and move into India, along with the westerly flow. They cause winter rains over the plains and snowfall in the mountains. They are of much importance for the cultivation of rabi crops.

Question 8. Give the characteristics and effects of the monsoon rainfall in India.
Answer : Characteristics of rainfall in India. The average annual rainfall in India is about 110cms. it is estimated than more than 85% of this rainfall is received in summer rainfall are as follows:
  • Monsoonal rainfall. Most of the rain is received from S.W. summer Monsoons during the period mid-June of mid-September. it is seasonal rainfall.
  • Uncertain rainfall. Summer rainfall is quite uncertain. Sometimes Monsoon start early resulting if floods. Often, the onset of Monsoon is delayed resulting in in delayed resulting in drought. the early or late retreat of Monsoon also result in serious drought.
  • Unequal distribution. The rainfall is unevenly distributed over the country. About 10% of the country gets more than 200 cm. of rain while 25% of the country gets less than 75 cms. of rain.
  • Heavy rainfall. Indian rainfall is heavy and down pouring type. it is often said. "it pours, it never rains in India."
  • Relief rainfall. the amount of rainfall is determined by the presence of mountains. high mountains force Monsoons to rise and given rain.
  • No continuity of rainfall. Summer rain is characteristic by breaks or dry spells.
  • Variable rainfall. Most of the areas have variable rainfall, as much as 30 cm. plus or minus. Due to variability in areas of low rain, famines result.

Chapter 4 CLIMATE |  Geography | CBSE Class 9th | Solved Exercises

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