ADDITIONAL QUESTIONS AND ANSWERS:
Answer the following questions :
1. What makes India a tropical country ?
Ans: The location of India in the northern hemisphere and the Tropic of Cancer passing through its centre makes India a tropical country .
2. Give one point of difference between weather and climate.
Ans: Weather is the condition of the atmosphere over an area for a short period of time whereas climate is the sum total of weather conditions of variations over a large area over a long period of time.
3. What are the four seasons that our country experiences. In which month do they experience the same?
Ans: On the basis of general atmospheric conditions, our country experiences four seasons: Winter (December to February), Summer (March to May), Monsoon or rainy season (June to September) and Retreating – monsoon (October and November).
4. What kind of extraordinary climatic variation does India have?
Ans: India has an extraordinary climatic variation in different regions, ranging from the tropical in the south to the temperate and alpine in the Himalayan ranges wherein the elevated regions receive sustained winter snowfall.
5. What influences the nations climate?
Ans: The nation’s climate is strongly influenced by the Himalayas and the Thar Desert.
6. India also has regional variations in climatic conditions. Give one example to show this.
Ans: For example, the temperature and precipitation differs from place to place and season to season. In the months of summer, the temperature in some parts of Rajasthan reaches 50⁰C whereas it would be only 20⁰ C in Jammu and Kashmir. In winter, the temperatures in Drass might fall as low as minus 45⁰ C where as in Tiruvananthapuram, it might be around 22⁰C.
7. The precipitation varies from region to region in its form and type. Explain briefly.
Ans: In the high altitude areas of Himachal Pradesh, Jammu Kashmir and Uttarkhand, the precipitation is in the form of snow, where as it rains in the rest of the country. The annual precipitation in Meghalaya is about 400 cms where as in the Ladakh and Western Rajasthan, it is as low as 10cms.
8. Briefly explain the factors that influence the climate of India.
Ans:
a) Location: India’s location in the Northern hemisphere and its closeness to the equator and the Tropic of Cancer influences the climate.
b) Altitude: The Himalayas act as barrier to the cold winds blowing from Central Asia moderating the temperatures in the Northern parts of India. Along the coastal plains, the climate and rainfall are influenced by the mountain ranges running parallel to the coast.
c) Pressure and Surface winds: The winds originating from the high-pressure belt in the northern hemisphere are deflected to the right due to the Coriolis force. The winds thereafter move towards the equatorial low-pressure area. As they blow from land, the winds are dry but as they travel over the sea they acquire moisture and India actually experiences monsoon type of climate.
9. What is Coriolis force?
Ans: Coriolis force is a force exerted by the air/ wind due to the Earth’s rotation.
10. What results in the reversal of winds?
Ans: During the winter months, a high pressure area develops to the north of Himalayas. So the winds blow out to the low pressure areas over the oceans in the south. During summer, an intense low-pressure area develops over interior Asia and north-west India while a high pressure develops over the Indian Ocean. This results in the reversal of winds.
11. What are Southwest monsoon winds?
Ans: The winds that carry moisture as they blow over the oceans in the southwest direction are known as the Southwest Monsoon Winds. It is these winds that bring extensive rainfall to India.
12. What are sub-tropical westerly jet streams?
Ans: The upper air circulation is controlled by Jet Stream. These streams are located between 27⁰ to 30⁰ north latitude. Over India, these Jet Streams blow in foot hills of Himalayas and are known as the sub-tropical westerly jet streams.
13. What are sub-tropical easterly jet stream?
Ans: The upper air circulation is controlled by Jet Stream. These streams are located between 27⁰ to 30⁰ north latitude. Over India, these Jet Streams blow in foot hills of Himalayas and are known as the sub-tropical westerly jet streams. Located at 14⁰ North latitude. They blow over the south Peninsular India.
14. Give the differences between the westerly jet streams and easterly jet streams.
Ans:
| Westerly Jet Streams | Easterly Jet Streams |
| 1. They are located between 270 to 300 North latitude | 1. They are located over 140 North latitude |
| 2. In India they blow in the foothills of the Himalayas | 2. In India they blow over the South Peninsular India |
| 3. These winds cause the western cyclonic disturbances . | 3. These winds cause a cooling effect that leads to condensation . |
15. What are the factors that influence monsoons in India? Explain each briefly .
Ans:
(a) Differential Heating and cooling of land and water: This creates low-pressure on land mass and high-pressure on water bodies .
(b) Inter Tropical Convergence Zone(ITCZ) shift: The equatorial trough is normally positioned over 5⁰ North. It moves towards the Ganga plain in the north in summer. The same trough is known as the monsoon trough in summer .
(c) High Pressure over Madagascar: The intensity and position of the high pressure are over Madagascar builds high pressure to the South of the Indian Ocean thus, influencing the monsoons in India .
(d) Tibetan Plateau: The summer creates strong vertical air currents. The low pressure over Tibet is formed at a height of 9kms above the sea level .
(e) Jet Stream: The movement of the westerly jet stream is towards the north of the Himalayas. The tropical easterly jet stream is seen during the summer months over the south peninsula India.
Other than this, pressure conditions over the southern oceans also influence the monsoon in India .
16. What is southern oscillation ?
Ans: Generally, when the South Pacific Ocean has high-pressure, there is low pressure over the tropical East India Ocean. Sometimes, there is a shift in this condition and the pressure over South Pacific is lesser than the Indian Ocean. This periodic change is known as Southern Oscillation .
17. What is the El –Nino ?
Ans: It is a series of changes in the climate affecting parts of the Pacific region every few years .
18. The pressure conditions are connected to another aspect – the El-Nino factor what is El Nino factor ?
Ans: Generally, a cold current moves along the Peruvian Coast of the Western region of South America. When a warm current begins to flow in the same area, the pressure conditions affect the monsoons. This is called the El-Nino factor .
19. When is El Nino known as ENSO ?
Ans: When El Nino is connected to the Southern Oscillation it is known as ENSO (EL Nino Southern Oscillation) .
20. India has monsoon type of climate. Why is this type of climate important for India ?
Ans: The entire economy, life of people and culture are influenced by the monsoon. Although, we experience a variety of temperature conditions, it is the monsoon that binds and influences our lives
The monsoons play an important role in giving us the climate rhythm known as seasons. The unevenness in its distribution temperature and rainfall also gives rise to a variety of flora and fauna. Indian economy is based on agriculture. The entire agriculture cycle is dependent on monsoon. Monsoons shape our decisions of what to grow and when to grow. Our festivals are influenced by the monsoon. Undoubtedly, it is the country’s monsoon which feeds the rivers or our lifelines .
21. How is the distribution of rainfall in India? Explain briefly .
Ans: Distribution of rainfall in India is highly uneven. The coastal areas receive over 400 cms of rainfall but in the western parts of Rajasthan and Gujarat, it is as less as 60 cms. The same trend is noticed in the interior parts of the Deccan Plateau, the east of the Sahyadris and the Leh region in Ladakh. Rest of the country receives moderate rainfall. Secondly, there is a variation in annual rainfall every year. The variation in rainfall is more prominent in the regions of low rainfall. The areas of high rainfall face floods where as low rainfall areas face droughts at the same time.
22. Which are the areas that receive low rainfall and why do they receive less rainfall. Explain .
Ans: Rainfall is low in some parts of Rajasthan, Thar Desert and Gujarat as there is no relief in these areas to check the Arabian Sea branch of monsoons. As the Aravallis lie parallel to the flow of the monsoon, the monsoons bypass Rajasthan and Gujarat unobstructed without providing any rainfall. Moreover, during the summer season, the temperature in parts like the Thar Desert of Rajasthan is so high that the monsoons passing over these areas get dry causing no rainfall.
-There is low rainfall on the leeward side of the Western Ghat and in the interiors of the Deccan Plateau because these areas come in the rain shadow zone. The Western Ghats on the western side and the Eastern Ghats on the eastern side do not allow the rain bearing winds to bypass them. The leeward side of the Western Ghats and the interior parts of the Deccan Plateau consequently receive very scanty rainfall .
23. What is rain shadow area? Explain briefly .
Ans: That side of the mountain which does not get much rain is known as the Rain Shadow Area. The winds after crossing the summits of the mountains descend along the slopes on leeward side of the mountains, but while descending, they get warmed up and become dry. The other reason is that the moist winds may not cross over the other side of the mountains which are too high as is in the case with the Himalayas which render Tibet a dry region .
24. What are the 4 types of seasons in India ?
Ans: India experiences four distinct types of seasons they are :
i) The Hot Weather Season .
ii) The Monsoon Season .
iii) Advancing Monsoon .
iv) Retreating Monsoon .
v) The Cold Weather Season .
25. What is Summer Solistice ?
Ans: As the apparent movement of the sun is towards the north, the global heat belt also shifts and the northern hemisphere experiences hot summer. This is called Summer Solistice .
26. In peninsular India the temperatures do not rise very high. Why ?
Ans: In peninsular India, the temperatures are not really very high due to the moderating effect of the seas .
27. Explain about ‘low pressure’ towards the end of May. Where does it spread ?
Ans: The high temperatures in the northern plains are associated with the formation of low-pressure towards the end of May. This low-pressure belt intensifies and spreads from the Thar desert in the west to Patna and Chota Nagpur Plateau in the east and south east .
28. What is loo ?
Ans: During the hot season, strong gusty winds blow during the day and these are known as loo .
29. Give some bad effects of the ‘loo’. (Disadvantages) .
Ans: These hot winds sometimes blow till late evenings. Direct exposure to the high temperatures of these winds may cause death. Dust storms are also common during this period .
30. Give one good effect of the loo . (Advantage)
Ans: These storms are sometimes accompanied with light rains and cool breeze, thus providing relief from the intense heat .
31. What is Kal Baisakhi? Where does it occur ?
Ans: Localized thunderstorms with downpours and violent winds combined at times with hail also occur. Such storms are known as Kal Baisakhi in West Bengal .
32. Pre-monsoon showers in Kerala, Karnataka and Goa are also called ‘mango showers’. Why ?
Ans: Pre-monsoon showers are also called the Mango showers, because they help in the early ripening of the mangoes .
33. What are monsoon winds? Explain .
Ans: The low-pressure belt on the northern plains intensifies by the end of May and early June. Monsoon winds originate from the sub-tropical areas of the southern oceans; as they blow towards the north, they carry large quantities of moisture from the oceans : They blow towards the north crossing the equator in the south-westerly direction and enter the Indian peninsula as southwest monsoon winds. It is the southwest monsoon winds which brings rain to the country. Monsoon winds are strong winds and they blow at speeds of about 30kms per hour .
34. How does the southwest monsoon winds bring about a change in the monsoon in India ?
Ans: The southwest monsoon brings in a change in weather conditions in India. The windward sides of the Western Ghats receive very heavy rains. Maximum rainfall is received in the north-east parts of the country. Mawsynram in the southern ranges of Khasi hills receives the highest rainfall. The intensity of rains decreases from the east to the west. Lowest rainfall receiving areas are in the western parts of the states of Rajasthan and Gujarat. South-West monsoons account for the rainfall along the Malabar Coast .
35. The rains are not continuous they break in. Why ?
Ans: The rains are not continuous; they break in between and cause dry and wet spells. This is due to the movement of monsoon trough, which moves north to south .
36. What will happen if the monsoon trough moves towards the Himalayas ?
Ans: If the monsoon trough moves towards the Himalayas, the Ganga plains experience a dry spell. The Himalayas on the other hand at the same time receive heavy rainfall .
37. What influences the amount of rainfall and duration of the monsoon season ?
Ans: Tropical depressions form over the Bay and Bengal and cross over to the mainland following the path of the monsoon trough. The intensity and frequency of these tropical depressions influences the amount of rainfall and the duration of the monsoon season .
38. Delta region of the eastern coast is frequently struck by cyclones. Explain why ?
Ans: The months of October and November are a period of transition from hot rainy season to dry winter conditions. In the second half of October, the mercury begins to fall at a rapid speed, especially in the northern region of India. The low pressure conditions, which were prevailing in the north of India, due to the hot season gets directed to the Bay of Bengal by November. This very shift causes cyclonic depression in the Andaman Sea. These tropical cyclones cause heavy and wide spread rains along the eastern coasts of India .
39. How is the Southwest monsoon wind formed ?
Ans: The South-East Trade winds from the Southern Hemisphere, when they cross the Equator and reach India, become the south-west monsoon winds .
40. Name the two branches of the southwest monsoon winds. Why are they divided into these branches ?
Ans: Due to the triangular shape of the Indian Peninsula, they are divided into two branches- The Arabian Sea Branch and the Bay of Bengal Branch .
41. Briefly describe the Arabian Sea Branch of the south west monsoons .
Ans: This branch of the monsoon wind is intercepted by the Western Ghats (Sahyadri Mountain). As a result the windward side of the Western Ghats receives heavy rainfall, more than 250cms. On the other hand the Deccan Plateau, which lies on the leeward side gets just less than 150cms of rainfall. Such region of low rainfall is known as rain shadow region. As we move further east the amount of rainfall decreases considerably. For example Mumbai gets 190cms of rainfall this season, whereas Pune gets 125cms of rainfall and Tanjavur gets only 85cms of rainfall .
42. What is Continentality ?
Ans: The seasonal contrast of temperatures is more prominent in the interiors than in the coastal areas. This is known as Continentality .
43. How does the monsoon ‘retreat’ after having completed its duration. Explain briefly .
Ans: The south west monsoon begins to retreat from the North Indian plains by the third week of September. The retreat of the monsoon is slow and steady. By the end of September it reaches in the Southern parts of Ganga valley. It completely retreats from whole Northern Plains by the end of October. By mid-November, only few pockets in southern and central India remain under the influence of the monsoon winds. Thus, the retreat of monsoon first starts from North and then it extends to the south .
44. What is October heat ?
Ans: The retreat of the monsoon is marked by clear skies and rise in temperature. While day temperatures are high, nights are cool and pleasant. Owing to the conditions of high temperature and humidity the weather becomes stagnant and oppressive. This is known as October Heat .
45. Write a short note on cold weather season .
Ans: After the retreat of the monsoon by November, the northern parts of the country experience rapid drop in temperatures. This marks the beginning of the winter season. This season generally continues till February.One can see frost in the north and snow on the higher slopes of the Himalayas. The northeast winds blow from land to sea, hence the season is dry.The weather has clear skies, low temperatures and humidity .
46. What are winter rains ?
Ans: Western disturbances that develop over the Mediterranean sea begin to flow from the north and northwest during this period. These winds bring in winter rains over the plains and snowfall in the Himalayas .
47. How is the rainy season in Goa? Explain briefly .
Ans: It begins with onset of south west monsoon winds. Monsoon generally reaches to Goa’s coast in the first week of June. But last few years there is variations in arrival of monsoon i.e. either last week of May or second week of June. During south west monsoon winds, velocity of winds varies between 40 to 60kms. per hour. The winds brings lot of moisture with clouds and clouds are notices almost 50-60mts. above the ground. The Sahyadri mountains play important role in controlling the movement of monsoons winds as a result Goa get heavy rainfall in the last week of June to last week of July. Many times cloud burst phenomena brings huge amount of rainfall during short period of time.After 15th August the intensity of rainfall decreases. Retreating of monsoon takes place in the second week of October .
48. What is the main weather phenomena of Goa in winter ?
Ans: Clear sky with bright sunlight, cool easterly winds, less air temperature are the main weather phenomena during winter season .
Fill in the blanks :
1. The natural environment of a region is influenced by three basic natural forces. They are Landforms , climate and drainage .
2. The climate of a region is influenced by its physiography and location .
3. India’s climate is described as the monsoon type of climate .
4. Full form of ITCZ is Inter Tropical Convergence Zone .
5. The pressure conditions are connected to another aspect the El. Nino factor .
6. Full form of ENSO is El Nino Southern Oscillation .
7. Mango showers are common in Karnataka, Kerala and Goa states .
8. Monsoon winds are strong winds and they blow at speeds of about 30 kms per hour .
9. The deltas of the Godavari,Krishna and Kaveri rivers are frequently hit by cyclones .
10. Goa has 3 seasons :
(i) Rainy season from June to October .
(ii) Winter season from November to February .
(iii) Summer season from March to May .