161) Why does the rainfall decrease from the East to the West in Northern India?
Answer: In summer, the monsoons rise both from the Bay of Bengal and the Arabian sea. The monsoons which rise from the Bay of Bengal cause heavy rainfall in the Brahmaputra valley and the Meghalaya hills (e.g., in Mawsynram). Because of the Himalayas, the monsoon winds then take a Western turn and move up the Ganga valley, but as they proceed Westwards, they become drier and therefore they cause less and less ram as they move forward. As such, Kolkata gets an annual rainfall of 119 cm, Patna 105 cm, Allahabad 76 cm and Delhi 56 cm.
162) Give an account of weather conditions and characteristics of the cold season.
Answer:The cold weather season begins from November in Northern India and stays till February. December and January are the coldest months in the Northern part of India.
(i) The weather is normally marked by clear sky, low temperatures, low humidity and feeble variable winds.
(ii) Days are warm and nights are cold. Frost is common in the North and higher slopes of the Himalayas experience snowfall.
(iii) During this season, the North-East trade winds blow from land to sea and hence for most parts or the country it is a dry season. Some amount of rainfall occurs on the Tamil Nadu coast from these winds as they blow there from sea to land.
(iv) A characteristic feature of the cold weather season over the Northern plains is the inflow of cyclonic disturbances from the West and the North-West. The low pressure systems originate over the Mediterranean sea and Western Asia and move into India along with the Westerly flow. They cause the much needed winter rams over the plains and snowfall in the mountains.
(v) Although the total amount of winter rainfall locally known as 'Mahawat' is small, it is of immense importance for the cultivation of Rabi crops.
(vi) The peninsular region does not have a well defined cold season. There is hardly any noticeable change in temperature pattern during winter due to the moderating influence of the sea. This types of question will not be asked in the examination. Only two or three sub-parts will be asked
163) Give reasons as to why seasonal reversal of wind direction takes place over the Indian sub-continent. the bulk of rainfall in India is concentrated over a few months. the Tamil Nadu coast receives winter rainfall. the delta region of the Eastern coast is frequently struck by cyclones. parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.
Answer:(a) The seasonal reversal of wind direction over the Indian sub-continent is the result of the Coriolis force. It is an apparent force caused by the Earths rotation. The Coriolis force is responsible for deflecting winds towards the right in the Northern Hemisphere and towards the left in the Southern Hemisphere.
(b) The rainfall received by India is largely due to the South-West monsoon winds. The duration of the monsoon is between 100 to 120 days. Hence, the bulk of rainfall received by the country is concentrated over a few months.
(c) During the winter season, North-East trade winds prevail over India. They blow from land to sea and hence for most part of the country, it is a dry season. However, the Tamil Nadu coast receives winter rainfall due to these winds. This is because in this region these winds blow from sea to land, thereby carrying moisture along with them.
(d) The delta region of the Eastern coast of India is frequently struck by cyclones. This is because the cyclonic depressions that originate over the Andaman sea are brought in by the sub-tropical Easterly jet stream blowing over peninsular India during the monsoon, as well as during the October to November period.
(e) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone because of the scanty rainfall received by these regions during the monsoon rains. The progressive decrease in the humidity of the winds of the Bay of Bengal branch causes the amount of rainfall to decrease from East to West in Northern India. As the leeward side is the rain-shadow area, the regions lying in this region receive very little rain from the Arabian sea branch. It is the windward side of the ghats that receives the maximum rain. This types of question will not he asked in the examination. Only two or three sub-parts will he asked.
164) Give the characteristics and effects of the monsoon rainfall in India, If there is too much rain, it causes floods and havoc all around. On the other hand, insufficient rain in a year or over some years results in drought, famine, food-insecurity, starvation and even deaths. This types of question will not he asked in the examination. Only two or three sub-parts will be asked.
Answer: Characteristics and effects of the monsoons or monsoon rainfall are
(i) The monsoons account for 90% of the rainfall received by India. Almost, every part of the country except the East coast of Tamil Nadu receives the bulk of rainfall from the summer monsoons.
(ii) The rainfall is neither continuous nor regular even in the wettest areas.
(iii) Overall rainfall is not the same each year. The monsoons may be strong or weak in a particular year depending on the intensity and frequency of the depression in the Bay of Bengal.
(iv) The monsoon rains are not evenly distributed over the country.
(v) A low pressure near the Himalayas may result in heavy rains in the hills, causing floods in the plains or the plains may face prolonged dry spells.
(vi) Sometimes the monsoon may burst too early or too late. There may be too long breaks or too many breaks in the monsoon, which may retreat too early or too late. All these factors upset the agricultural operations, making agriculture in India a gamble. Sometimes, the effects of the monsoon or its uneven distribution create a number of problems. If there is too much rain, it causes floods and havoc all around. On the other hand, insufficient rain in a year or over some years results in drought, famine, food-insecurity, starvation and even deaths. This types of question will not he asked in the examination. Only two or three sub-parts will be asked.
165) Describe the climatic conditions of India during retreating monsoon. Or Describe any three main features of retreating monsoon.
Answer: Following are the phenomena of the retreating monsoons
(i) It occurs in the months of October and November.
(ii) The monsoon trough or the low pressure trough over the Nothern plains becomes weaker and it is gradually replaced by a high-pressure system.
(iii) The South-West monsoon winds weaken and start withdrawing gradually. The months of October-November from a period of transition from hot rainy season to dry winter conditions.
(iv) The retreat of the monsoon is marked by clear skies and rise in temperature.
(v) Day temperatures are high, nights are cool and pleasant. The weather becomes rather oppressive during the day, it is commonly known as 'October heat'.
166) Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Answer: There are regional variations in the climatic conditions of India which can be understood with the help of the following examples (i) The months of December and January are the coldest in Northern India where the temperature ranges between 10o-15oC. (ii) In summer, the mercury occasionally touches 50oC in some parts of the Rajasthan desert, whereas it might be around 20oC in Pahalgam in Jammu and Kashmir. (iii) On a winter night temperature at Drass town in Jammu and Kashmir may be as low as -40oC. Thiruvananthapuram on the other hand may have a temperature of 22o C. (iv) Annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and Western Rajasthan. In the Himalayas precipitation is in the form of snow fall. (v) Coastal regions do not experience much variation in temperature pattern due to the moderating influence of the sea.
167) Discuss the mechanism of monsoons.
Answer: The climate of India is described as the monsoon type
(i) The factors affecting the climate of an area are latitude, altitude, pressure and wind system as well as distance from the sea.
(ii) India lies in the region of North-Easterly winds. These winds originate from the sub-tropical high pressure belt in the Northern Hemisphere, get deflected to the right due to the Coriolis force and move on towards the equatorial low pressure area.
(iii) In summer, a low pressure area develops over interior Asia and North-Western India. This causes complete reversal of the direction of the winds. Air moves from the high pressure area over the Southern Indian Ocean, crosses the equator and turns right towards the low pressure areas over the Indian sub-continent. These are known as the South-West monsoon winds. These winds blow over the warm oceans, gather moisture and bring widespread rainfall over the mainland of India.
(iv) The upper air circulation in this region is dominated by a Westerly flow.
(v) The duration of the monsoon is between 100-120 days from early June to mid-September.
(vi) The Southern Oscillation (SO) and jet streams also affects the monsoon.
168) "India has diverse climatic conditions". Explain by giving two examples each of temperature and precipitation. Or "India has diverse climatic conditions." Support this statement by giving three examples. Or Describe the regional variation in climate conditions of India with the help of suitable examples.
Answer: Regional variations in the climatic conditions in India
(i) In summer, the mercury occasionally touches 50o C in some parts of the Rajasthan desert, whereas it may be around 20o C in Pahalgam in Jammu and Kashmir.
(ii) On a winter night, temperature at Drass in Jammu and Kashmir may be as low as-45oC.Thiruvananthapuram, on the other hand, may have a temperature of 22oC.
(iii) The annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and Western Rajasthan.
(iv) Most parts of the country receive rainfall from June to September. But some parts like the Tamil Nadu coast gets a large portion of its rain during October and November.
(v) While precipitation is mostly in the form of snowfall in the upper parts of Himalayas it rains over the rest of the country.
(iv) Coastal areas experience less contrasts in temperature conditions. Seasonal contrasts are more in the interior of the country.
(vii) There is decrease in rainfall generally from East to West in the Northern plains.
169) "The monsoon is considered a unifying bond in India". What moral values you could inculcate from this statement?
Answer:Following are the moral values that the very unifying nature of the monsoon inculcate in us (i) Bringing happiness to all without any bias.
(ii) Service to the mankind without any desire.
(iii) Developing the feelings of integrity and oneness.
(iv) Respect for variations and differences.
(v) Treating all whether it be a plant, an animal or humans equally to the best.
(vi) Providing life and livelihood to all.
(vii) Promoting equality and uniformity.
(viii) Leading a routined and disciplined life.
(ix) Respecting the value of time.
170) Some terms related to the climate of India are given below. Classify them into the season which they fall (Winter, Summer, Advancing Monsoon and Retreating Monsoon).
Burst of Monsoon
Western cyclonic disturbance
Break in monsoon
North-East trade winds
Low pressure monsoon trough
Answer: Terms of Indian Climate
Burst of monsoon
Break in monsoon
Western cyclonic disturbance
North-East trade winds
Low pressure monsoon trough
171) Why does most of Tamil Nadu not get much rain from the South-West monsoon during the period June-September?
Answer: This area falls in the leeward region of the Sahyadris (Western Ghats) and so it does not receive rain from the Arabian sea branch of the monsoon. The Bay of Bengal branch of the monsoon travels North-Eastwards to Asom and so bypasses Tamil Nadu almost totally. Thus, Tamil Nadu does not get rainfall from either branch of the advancing monsoon.
172) Choose the correct answer from the four alternatives given below (i) Which one of the following places receives the highest rainfall in the world? (a) Silchar (b) Mawsynram (c) Cherrapunji (d) Guwahati
173) The wind blowing in the Northern plains in summers is known as (a) Kaal Baisakhi ( b) Loo (c) Trade Winds (d) None of these
174) 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) South West monsoon
175) Monsoon arrives in India approximately in (a) early May (b) early July (c) early June (d) early August
176) Which one of the following characterises the cold weather season in India? (a) Warm days and warm nights (b) Warm days and cold nights (c) Cool days and cold nights (d) Cool days and warm nights