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Q. 1 Differentiate between weather and climate.
Answer Key Points: -
| Aspects | Weather | Climate |
|---|---|---|
| Definition | Weather refers to short-term atmospheric condition of a particular area at a specific period of time. | Climate refers to the sum total of weather conditions and variations over a large area for a long period of time (more than 30 years). |
| Durability | The weather of a place can change within a short period like minutes, hours, days, etc. | The climate of an area includes the information of long-term average atmospheric conditions observed over decades. |
| Affected By | Weather may be affected by just one condition of atmosphere like temperature, pressure, humidity, cloudiness, wind, precipitation, rain, flooding, ice storms, etc. | The climate is the long term observations of all the atmospheric conditions at any location like humidity, temperature, wind, and sunshine etc. |
| Influence | The weather may affect the day-to-day occupation, and it may affect transportation services, agriculture, etc. | Climate significantly affects agriculture, industries, and the livelihood of the peoples. |
| Changes Observed | The changes in the weather condition can be observed very frequently. | Climate conditions change over a long period. |
| Studied By | The meteorological department of a place observes the changes in weather conditions. The study of weather forecasting is known as meteorology. | Institutes of climate studies observe and predict the changes in climate. This study is called climatology. |
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Q. 2 What is annual range of temperature? Explain it by giving examples. Or
Explain the spatial variation in temperature in India.
Answer Key Points: -
The difference between the maximum average temperature and minimum average temperature of a place over twelve months is known as annual range of temperature.
1) In the summer the mercury occasionally touches 55°C in the western Rajasthan, it drops down to as low as minus 45°C in winter around Leh.
2) Churu in Rajasthan may record a temperature of 50°C or more on a June day while the mercury hardly touches 19°C in Tawang (Arunachal Pradesh) on the same day.
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3) On a December night, temperature in Drass (Jammu and Kashmir) may drop down to minus 45°C while Thiruvananthapuram or Chennai on the same night records 20°C or 22°C.
4) In Kerala and in the Andaman Islands, the difference between day and night temperatures may be hardly seven or eight degree Celsius. But in the Thar Desert, if the day temperature is around 50°C, at night, it may drop down considerably up to 15°-20°C.
These examples confirm that there are seasonal variations in temperature from place to place and from region to region in India.
Q. 3 Explain the spatial variation in the rainfall throughout the country. Or
What is the average amount of rainfall over the plains of India?
Answer Key Points: -
There is great variation in rainfall throughout the country.
1) Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall over 1,080 cm in a year, Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period.
2) The annual precipitation is less than 10 cm in the north-west Himalayas and the western deserts; it exceeds 400 cm in Meghalaya.
3) In some parts of Khasi and Jaintia hills, the rainfall exceeds 1,000 cm. In the Brahmaputra valley and the adjoining hills, the rainfall is less than 200 cm.
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4) Rainfall between 100-200 cm is received in southern parts of Gujarat, east Tamil Nadu, North-eastern Peninsular covering Orissa, Jharkhand, Bihar, eastern Madhya Pradesh, Northern Ganga Plain along the sub-Himalayas and the Cachar valley and Manipur.
5) Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50 and 100 cm.
Q. 4 Which areas have more than 50 cm and less than 5 cm of rainfall in July? Why is it so?
Answer Key Points: -
Most areas of the country have more than 50 cm of rainfall in July. The Western Rajasthan (Thar Desert) and the North-eastern Ladakh experience less than 5 cm. of rainfall in July.
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Due to parallel situated of Aravalli’s, lack of vegetation, high temperatures and non-condensation of moisture in Western Rajasthan rainfall is very scanty. The Zaskar range does not allow the monsoon winds to reach North-eastern Ladakh. So it also receives very scanty rainfall during July.
Q. 5 Enumerate the factors that influence the climate of the Subcontinent of India. Or
Explain the factors affecting climate of a place/India. Or
Describe the main climatic controls of a place.
Answer Key Points: -
1) Latitude: - Due to the curved surface of the Earth, the amount of solar energy received varies according to latitude. The Tropic of Cancer divides India into subtropical (North) and tropical (South) areas, so the tropical area receives more heat than the subtropical area.
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2) Distribution of Land and Water: - India is flanked by the Indian Ocean on three sides in the south and bordered by a high and continuous mountain-wall in the north. As compared to the landmass, water heats up or cools down slowly. This differential heating of land and sea creates different air pressure zones in different seasons in and around the Indian subcontinent. Difference in air pressure causes reversal in the direction of monsoon winds.
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3) The Distance From The Sea: - The Sea exerts a moderating influence on a climate as the distance from the sea increases its moderating influence decreases and the people experience extreme weather conditions. This condition is known as continentality. The coastal areas in the South India experience equable climatic conditions.
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4) Altitude: - Temperature decreases with height. Due to thin air, places in the mountains are cooler than places on the plains. For example, Agra and Darjiling are located on the same latitude, but temperature of January in Agra is 16°C whereas it is only 4°C in Darjiling.
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5) Relief Features: - Nature of Relief plays a major role in determining the climate of a place e.g. high mountains act as barriers for cold or hot winds; they may also cause precipitation. Desert soil has the capacity to hold more heat which leads to rise in temperature.
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6) The Pressure And Winds: - The pressure and the wind system of an area depend on the latitude and altitude of the place. a) During summer low pressure is created over interior Asia as well as India, this leads to incoming of South-West Monsoon winds causing rainfall.
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b) During winter the high pressure area north of the Himalayas is responsible for withdrawal of these Monsoon winds.
Q. 6 What is the Inter-Tropical Convergence Zone (ITCZ)? How does it attract south monsoon? What are the important factors which influence the mechanism of Indian weather?
Answer Key Points: -
ITCZ is the zone near the Equator from where the north-east trade winds and the south-east trade winds meet each other. It changes its position with the effect of the vertical rays of the sun. It is near the Tropic of Cancer in the north in summer season and near the Tropic of Capricorn in the south in the winter season at about 25°N, as a result of which the south-east trade winds cross over the equator and enter in India as the south-west monsoon.
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Factors influencing the mechanism of Indian weather are: -
1) Surface distribution of pressure and winds include monsoon, location of low and high pressure.
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2) Upper air circulation which includes global weather conditions like air masses and the jet stream.
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Q. 7 What are the characteristics of Western Cyclonic disturbances of the Indian climate?
Answer Key Points: -
1) The cyclones developed near the Mediterranean Sea are termed as western disturbances.
2) They move towards India through Iran and Pakistan.
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3) They come under the influence of westerly jet stream which brings them to the northern part of India in the winter season.
4) They cause rain in the north-west part of the plain of India during winter.
Q. 8 Describe the mechanism of the Monsoon. Or
Explain the nature of onset of Indian monsoon.
Answer Key Points: -
1) Differential Heating and Cooling of Land and Water: - 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.
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2) Shift of The ITCZ: - The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator – also known as the Monsoon trough during the Monsoon season).
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3) High-Pressure Over Madagascar: - The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affects the Indian Monsoon.
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4) Heating of Tibetan Plateau: - The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.
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5) Jet Stream: - The movement of the westerly Jet Stream to the north of the Himalayas and the presence of the tropical easterly Jet Stream over the Indian peninsula during summer.
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Q. 9 Explain Rain-bearing Systems of Rainfall in India.
Answer Key Points: -
There seem to be two rain-bearing systems in India.
1) First originate in the Bay of Bengal causing rainfall over the plains of north India.
2) Second is the Arabian Sea current of the southwest monsoon which brings rain to the west coast of India. Much of the rainfall along the Eastern Ghats is orographic as the moist air is obstructed and forced to rise along the Ghats. The intensity of rainfall over the west coast of India is, however, related to two factors: -
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a) The offshore meteorological conditions.
b) The position of the equatorial jet stream along the eastern coast of Africa.
The rain which comes in spells, displays a declining trend from west to east over the west coast, and from the southeast towards the northwest over the North Indian Plain and the northern part of the Peninsula.
Q. 10 What is EI-Nino? How is it related to Indian monsoon? Or
Define El-Nino. What are features of El-Nino?
Answer Key Points: -
1) The word EI-Nino means ‘Child Christ’ because this current appears around Christmas in December. December is a summer month in Peru (Southern Hemisphere).
2) El-Nino is used for forecasting long-range of monsoon rainfall. The system involves the ocean and atmospheric phenomena with the appearance of warm winds off the coast of Peru in the Eastern Pacific which affect the weather.
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3) EI-Nino is a complex weather system that appears once every three to seven years, bringing drought, floods and other weather extremes to different parts of the world.
4) The system involves oceanic and atmospheric phenomena with the appearance of warm currents off the coast of Peru in the Eastern Pacific and affects weather in many places including India.
5) EI-Nino is merely an extension of the warm equatorial current which gets replaced temporarily by cold Peruvian current or Humboldt Current. This current increases the temperature of water on the Peruvian coast by 10°C. This results in: -
a) The distortion of equatorial atmospheric circulation.
b) Irregularities in the evaporation of sea water.
c) Reduction in the amount of planktons which further reduces the number of fish in the sea.
Q. 11 What is meant by break in the monsoon? Or
What is Break in Monsoon? What are its causes? When is the monsoon expected to break in Kerala and reach the plains of Punjab?
Answer Key Points: -
During the south-west monsoon period after having rains for a few days, if rain fails to occur for one or more weeks, it is known as break in the monsoon. These dry spells are quite common during the rainy season. These breaks in the different regions are due to different reasons: -
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1) In northern India rains are likely to fail if the rain-bearing storms are not very frequent along the monsoon trough or the ITCZ over this region.
2) Over the west coast the dry spells are associated with days when winds blow parallel to the coast. Breaking of the Monsoon in Kerala: -Beginning of June, reaching Punjab: First week of July.
Q. 12 Explain the important features of Winter Season of India.
Answer Key Points: -
1) The Cold Weather Season in India exists between mid-November and February in Northern India. December and January are the coldest months.
2) The day time average temperature lies between 10-15°C in the north eastern states in the plain areas.
3) During the cold season, the days are warm and nights are cold.
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4) When temperature decreases, frost is commonly experienced in Northern India.
5) This is dry season in most parts of the country as northeast trade winds blow from land to sea.
6) Many cyclonic disturbances occur over northern India during this time. These results in rainfall during winters and snow fall in the Himalayan regions. This rainfall helps in the cultivation of the Rabi crops.
Q. 13 Give the main features of Hot Weather (Summer) Season.
Answer Key Points: -
1) The summer season in India exists between the month of March and June.
2) The highest temperature of 35°C to 45°C is recorded in the Northern Plains.
3) During the summer season, a local hot wind called the ‘Loo’ blows in the northern parts of the country.
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4) During this season, thunder storms known as ‘Kalbaisakhi’ hit the states of West Bengal and Assam and leads to heavy rainfall.
5) It also rains in coastal Kerala and Karnataka. These showers are known as ‘Mango showers’ as they help in the early ripening of mangoes.
6) The southern states do not experience heat because of closeness to the sea.
Q. 14 Explain some local storms of hot weather season in India.
Answer Key Points: -
1) Mango Shower: - Towards the end of summer, there are pre- monsoon showers which are a common phenomenon in Kerala and coastal areas of Karnataka. Locally, they are known as mango showers since they help in the early ripening of mangoes.
2) Blossom Shower: - With this shower, coffee flowers blossom in Kerala and nearby areas.
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3) Nor Westers: - These are dreaded evening thunderstorms in Bengal and Assam. Their notorious nature can be understood from the local nomenclature of ‘Kalbaisakhi’, a calamity of the month of Baisakh. These showers are useful for tea, jute and rice cultivation. In Assam, these storms are known as “Bardoli Chheerha” or ‘Tea Showers’.
4) Loo: - Hot, dry and oppressing winds are blowing in the Northern plains from Punjab to Bihar with higher intensity between Delhi and Patna.
Q. 15 Explain the important features of Advancing Monsoon Season of India. Or
Why India gets a monsoon named as south-west monsoon?
Answer Key Points: -
1) The low-pressure condition over the northern plains attracts the trade winds of the southern hemisphere. As these winds blow over warm oceans, they bring abundant moisture to the subcontinent.
2) The windward side of the Western Ghats receives very heavy rainfall, and the Deccan Plateau and parts of Madhya
Pradesh also receive some amount of rain in spite of lying in the rain shadow area.
3) After crossing the equator, they follow a southwesterly direction. That is why they are known as southwest monsoons.
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4) The maximum rainfall of this season in the world is received by Mawsynram in the southern ranges of the Khasi Hills.
5) They blow during the months of June to September.
6) These blow from the high pressure area on the sea to the low pressure area on the land.
7) These blow into India in two branches, i.e., the Arabian Sea and the Bay of Bengal branch.
Q. 16 Why Mawsynram and Cherrapunji get very high rainfall?
Answer Key Points: -
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Mawsynram receives the highest amount of rainfall in the world in the rainy season because it is surrounded by the North-east hills of India, mainly Khasi, Garo, Jaintia in Meghalaya plateau is funnel-shaped. The Bay of Bengal branch of the south-west monsoon is enclosed by these hills resulting in the heaviest amount of rains.
Q. 17 Give the main characteristics of the monsoons rainfall.
Answer Key Points: -
1) Rainfall received from the southwest monsoons is seasonal in character, which occurs between June and September.
2) Monsoonal rainfall is largely governed by relief or topography. For instance the windward side of the Western Ghats registers a rainfall of over 250 cm.
3) During the southwest monsoon period, the monsoon rainfall has a declining trend with increasing distance from the sea. Kolkata receives 119 cm, Patna 105 cm, Allahabad 76 cm and Delhi 56 cm.
4) The monsoon rains occur in wet spells of few days duration at a time. The wet spells are interspersed with rainless interval known as ‘breaks’.
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5) The summer rainfall comes in a heavy downpour leading to considerable run off and soil erosion.
6) Monsoons play a pivotal role in the agrarian economy of India because over three-fourths of the total rain in the country is received during the southwest monsoon season.
7) Its spatial distribution is also uneven which ranges from 12 cm to more than 250 cm.
8) The beginning of the rains sometimes is considerably delayed over the whole or a part of the country.
9) The rains sometimes end considerably earlier than usual, causing great damage to standing crops and making the sowing of winter crops difficult.
Q. 18 Explain the meaning of retreating of monsoon. Give its features.
Answer Key Points: -
1) During October and November, the south-west monsoon winds become weaker and start retreating.
2) The retreat of the monsoon is marked by clear skies and an increase in mercury level in the northern plains.
3) This increase in temperature along with high level of humidity is termed as ‘October heat’.
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4) At this time, the low pressure conditions shift to the Bay of Bengal giving rise to cyclonic depressions. These cyclonic depressions often result in the destruction of life and property generally on the eastern and southern coasts.
5) By the beginning of October, the low pressure covers northern parts of the Bay of Bengal and by early November, it moves over Karnataka and Tamil Nadu.
6) By the middle of December, the center of low pressure is completely removed from the Peninsula.
Q. 19 Where do tropical cyclones originate? Which states do they hit the most? Or
Describe the main features of Tropical Cyclones.
Answer Key Points: -
Tropical cyclones originate over the Bay of Bengal and the Indian Ocean. These tropical cyclones have very high wind velocity and heavy rainfall and hit the Tamil Nadu, Andhra Pradesh and Orissa coast.
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1) The cyclones which originate and travel in the tropical zone are known as tropical cyclones.
2) These cyclones are often very destructive.
3) They originate in the Andaman Sea in the month of November.
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4) The low-pressure conditions, over north-western India, get transferred to the Bay of Bengal by early November. This shift is associated with the occurrence of cyclonic depressions.
5) These cyclones generally cross the eastern coasts of India and cause heavy and widespread rain.
Q. 20 Explain the distribution of rainfall in India.
Answer Key Points: -
The average annual rainfall in India is about 125 cm, but it has great spatial variations.
1) Areas of High Rainfall: - The highest rainfall occurs along the west coast, on the Western Ghats, as well as in the sub-Himalayan areas is the northeast and the hills of Meghalaya. Here the rainfall exceeds 200 cm. In some parts of Khasi and Jaintia hills, the rainfall exceeds 1,000 cm. In the Brahmaputra valley and the adjoining hills, the rainfall is less than 200 cm.
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2) Areas of Medium Rainfall: - Rainfall between 100 and 200 cm is received in the southern parts of Gujarat, east Tamil Nadu, northeastern Peninsula covering Odisha, Jharkhand, Bihar, eastern Madhya Pradesh, northern Ganga plain along the sub-Himalayas and the Cachar Valley and Manipur.
3) Areas of Low Rainfall: - Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50 and 100 cm.
4) Areas of Inadequate Rainfall: - Parts of the Peninsula, especially in Andhra Pradesh, Karnataka and Maharashtra, Ladakh and most of western Rajasthan receive rainfall below 50 cm. Snowfall is restricted to the Himalayan region.
Q. 21 Define ‘climatic region’? What are the bases of Koeppen’s classification? Or
Explain major climatic types of India based on Koeppen’s scheme.
Answer Key Points: -
A climatic region has a homogeneous climatic condition which is the result of a combination of factors. Koeppen gave his scheme of Climatic classification on monthly values of temperature and precipitation. He identified five following climatic types: -
1) Tropical climates, where mean monthly temperature throughout the year is over 18°C.
2) Dry climates, where precipitation is very low in comparison to temperature. If dryness is less, it is semiarid (S); if it is more, the climate is arid (W).
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3) Warm temperate climates, where mean temperature of the coldest month is between 18°C and minus 3°C.
4) Cool temperate climates, where mean temperature of the warmest month is over 10°C, and mean temperature of the coldest month is under minus 3°C.
5) Ice climates, where mean temperature of the warmest month is less than 10°C.
Q. 22 How economic life in India is affected by monsoon? Or
“Monsoon is a gambling for Indian farmers.” Explain.
Answer Key Points: -
1) The entire agricultural cycle of India revolve around Monsoon. In India about 64% people depend on agriculture for their livelihood and agriculture itself is based on southwest monsoon.
2) Except Himalayas all the parts of the country have temperature above the threshold level to grow the crops or plants throughout the year.
3) Variability of rainfall brings droughts or floods every year in some parts of the country.
4) Agricultural development of India depends on timely and adequately distributed rainfall. If it fails, agriculture is adversely affected particularly in those regions where means of irrigation are not less.
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5) Sudden monsoon burst creates problem of soil erosion over large areas in India.
6) Winter rainfall by temperate cyclones in north India is highly beneficial for Rabi crops.
7) Regional climatic variation in India is reflected in the vast variety of food, clothes and house types.
8) Sudden monsoon burst creates problems of soil erosion over large areas in India.
9) Winter rainfall by temperate cyclones in north India is highly beneficial for Rabi crops.
10) Regional climatic variation in India is reflected in the vast variety of food, clothes and house types.
Q. 23 “In spite of abundant rainfall, India is a water thirsty land”. Why is it so?
Answer Key Points: -
India is a water thirsty land in spite of abundant rainfall. This is because of the following factors: -
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1) Occurrence of rainfall in a few months (from June to September).
2) Rapid run off and the quick evaporation of rainwater.
3) Long breaks and delays in the Monsoons.
4) High demands of water due to larger population.
Q. 24 Define ‘drought’ and its various types.
Answer Key Points: -
Drought is a condition in which the amount of water needed for evapotranspiration exceeds the amount of water available for precipitation and soil. Droughts are of three types: -
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1) Permanent Drought: - Permanent drought is characterised by the arid climate in which vegetation is sparse and hardy, fully adapted to water shortage.
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2) Seasonal Drought: - Seasonal drought is found in dry and rainy seasons. Most of the parts of India suffer from this kind of drought.
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3) Contingent Drought: - Contingent drought is irregular with variable rainfall and occurs in any season but frequently in sub-humid climates.
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Q. 25 What is Global Warming? What are the effects of Global Warming? Or
What is global warming? Give its causes and effects.
Answer Key Points: -
Global warming is a gradual increase in the earth’s average surface temperature over the past one to two centuries, generally due to the greenhouse gases caused by increased levels of carbon dioxide, CFCs, and other pollutants.
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Causes of Global Warming: -
1) Carbon dioxide is the major source of global warming. This gas is released to the atmosphere by burning of fossil fuel.
2) Other gases like methane, chlorofluorocarbons, ozone and nitrous oxide which are present in much smaller concentrations in the atmosphere, together with carbon dioxide are known as greenhouse gases. These gases are contributing to global warming.
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3) Rapid industrialization and technological changes, the revolution in agriculture and transport sectors has resulted in large supplies of carbon dioxide and methane which cause global warming.
Effects of Global Warming: -
1) Due to global warming the polar ice caps and mountain glaciers would melt and the amount of water in the ocean would increase.
2) Melting of glaciers and sea-ice due to global warming leads to rise in the sea level up to 48 cm by the end of twenty first century.
3) Increase the incidence of annual flooding.
4) Insect-borne diseases like malaria, and leads to shift in climatic boundaries, making some regions wetter and other dries.
5) Agricultural pattern would shift and human population as well as the ecosystem would experience change.
6) The peninsular India would be submerged.
