Indian Geography Climate

Question 1

Weather climate

Answer 1

Weather is the momentary state of the atmosphere while climate refers to the average of the weather conditions over a longer period of time. Weather changes quickly, may be within a day or week but climate changes imperceptively and may be noted after 50 years or even more.

Question 2

Climate of India

Answer 2

Monsoon type with variations- sub-types of monsoon climate.

Question 3

FACTORS DETERMINING THE CLIMATE OF INDIA

Answer 3

Latitude, distribution of land and water, distance from the sea, altitude, relief including Himalayas

Question 4

How does Latitude affect the climate of India?

Answer 4

Tropic of Cancer passes through the central part of India in east-west direction. Thus, northern part of the India lies in sub-tropical and temperate zone and the part lying south of the Tropic of Cancer falls in the tropical zone. The tropical zone being nearer to the equator, experiences high temperatures throughout the year with small daily and annual range. Area north of the Tropic of Cancer being away from the equator, experiences extreme climate with high daily and annual range of temperature.

Question 5

How does The Himalayan Mountains affect the climate of India?

Answer 5

The lofty Himalayas in the north along with its extensions act as an effective climatic divide. The towering mountain chain provides an invincible shield to protect the subcontinent from the cold northern winds. These cold and chilly winds originate near the Arctic circle and blow across central and eastern Asia. The Himalayas also trap the monsoon winds, forcing them to shed their moisture within the subcontinent.

Question 6

How does Distribution of Land and Water affect the climate of India?

Answer 6

India is flanked by the Indian Ocean on three sides in the south and girdled 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.

Question 7

How does Distance from the Sea affect the climate of India?

Answer 7

Areas in the interior of India are far away from the moderating influence of the sea. Such areas have extremes of climate. That is why, the people of Mumbai and the Konkan coast have hardly any idea of extremes of temperature and the seasonal rhythm of weather. On the other hand, the seasonal contrasts in weather at places in the interior of the country such as Delhi, Kanpur and Amritsar affect the entire sphere of life.

Question 8

How does Altitude affect the climate of India?

Answer 8

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.

Question 9

elements of weather

Answer 9

(temperature, pressure, wind direction and velocity, humidity and precipitation, etc.)

Question 9

How does Relief affect the climate of India?

Answer 9

the physiography or relief of India also affects the temperature, air pressure, direction and speed of wind and the amount and distribution of rainfall. The windward sides of Western Ghats and Assam receive high rainfall during June-September whereas the southern plateau remains dry due to its leeward situation along the Western Ghats.

Question 10

Wrt air pressure and winds, mechanism of Weather in the Winter Season

Answer 10

Surface Pressure and Winds : high pressure area near Central and West Asia leads to dry air blowing towards Himalyas which collide with trade winds over Northwestern India, or sometime Ganga plain.
Jet Stream and Upper Air Circulation :3 km above the surface jet streams blow from west to east parallel to the Himalayas. Tibetan highlands bifurcate them–One of its branches blows to the north of the Tibetan highlands, while the southern branch blows in an eastward direction, south of the Himalayas.
Western Cyclonic Disturbance and Tropical Cyclones : The western cyclonic disturbances which enter the Indian subcontinent from the west and the northwest during the winter months, originate over the Mediterranean Sea and are brought into India by the westerly jet stream. Tropical cyclones originate over the Bay of Bengal and the Indian ocean.

Question 11

Inter Tropical Convergence Zone (ITCZ) wrt India and monsoons

Answer 11

The Inter Tropical Convergence Zone (ITCZ) is a low pressure zone located at the equator where trade winds converge, and so, it is a zone where air tends to ascend. In July, the ITCZ is located around 20°N-25°N latitudes (over the Gangetic plain), sometimes called the monsoon trough. This monsoon trough encourages the development of thermal low over north and northwest India. Due to the shift of ITCZ, the trade winds of the southern hemisphere cross the equator between 40° and 60°E longitudes and start blowing from southwest to northeast due to the Coriolis force. It becomes southwest monsoon. In winter, the ITCZ moves southward, and so the reversal of winds from northeast to south and southwest, takes place. They are called northeast monsoons.

Question 12

Wrt air pressure and winds, mechanism of Weather in the in the Summer Season

Answer 12

Surface Pressure and Winds : ITCZ near equator shifts northwards and the westerly jet streams withdraw in cause-effect relationship. The moist maritime tropical air that rushes towards the subconnent is called he monsoon wind.
Jet streams- Easterly jet stream roughly over southern part of peninsula in June
Easterly Jet Stream and Tropical Cyclones : The easterly jet stream steers the tropical depressions into India. These depressions play a significant role in the distribution of monsoon rainfall over the Indian subcontinent

Question 13

Onset of the Monsoon

Answer 13

During April and May when the sun shines vertically over the Tropic of Cancer, the large landmass in the north of Indian ocean gets intensely heated. This causes the formation of an intense low pressure in the northwestern part of the subcontinent.
Since the pressure in the Indian Ocean in the south of the landmass is high as water gets heated slowly, the low pressure cell attracts the southeast trades across the Equator. These conditions help in the northward shift in the position of the ITCZ. The southwest monsoon may thus, be seen as a continuation of the southeast trades deflected towards the Indian subcontinent after crossing the Equator. These winds cross the Equator between 40°E and 60°E longitudes. The shift in the position of the ITCZ is also related to the phenomenon of the withdrawal of the westerly jet stream from its position over the north Indian plain, south of the Himalayas. The easterly jet stream sets in along 15°N latitude only after the western jet stream has withdrawn itself from the region. This easterly jet stream is held responsible for the burst of the monsoon in India.

Question 14

Entry of Monsoon into India

Answer 14

The southwest monsoon sets in over the Kerala coast by 1st June and moves swiftly to reach Mumbai and Kolkata between 10th and 13th June. By mid- July, southwest monsoon engulfs the entire subcontinent

Question 15

Rain-bearing Systems and Rainfall Distribution

Answer 15

2. First originate in the Bay of Bengal causing rainfall over the plains of north India. Second is the Arabian Sea current of the south- west monsoon which brings rain to the west coast of India. Much of the rainfall along the Western 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: (i) offshore meteorological conditions. (ii) The position of the equatorial jet stream along the eastern coast of Africa.
   The frequency of the tropical depressions originating from the Bay of Bengal varies from
   year to year. Their paths over India are mainly determined by the position of ITCZ which is generally termed as the monsoon trough.

Question 16

Break in the Monsoon

Answer 16

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:
(i) 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.
(ii) Over the west coast the dry spells are associated with days when winds blow parallel to the coast.

Question 17

THE RHYTHM OF SEASONS

Answer 17

(i) the cold weather season (ii) the hot weather season
(iii) the southwest monsoon season (iv) the retreating monsoon season.

Question 18

The Cold Weather Season Temperature

Answer 18

Temperature : Usually, the cold weather season sets in by mid-November in northern India. December and January are the coldest months in the northern plain. The mean daily temperature remains below 21°C over most parts of northern India. The night temperature can go below 0. Reasons for excesive cold-1. Faraway from moderating sea influence 2. Snowfall in Himalayas 3. Cold winds from Caspian Sea and Turkmenistan. The Peninsular and coastal regions of India, however, does not have any well-defined cold weather season

Question 19

The Cold Weather Season pressure and winds

Answer 19

3 points as discussed + feeble high and low presure gradients north and south india respectively cause wind to blow from N to S.

Question 20

The Cold Weather Season Rainfall

Answer 20

Mostly no rainfall since wind moving from land to sea has little moisture and due to anti cyclonic circulation onland, the possibility of rainfall from them reduces. However, there are some exceptions to it:
1. In northwestern India, some weak temperate cyclones from the Mediterranean sea cause rainfall in Punjab, Haryana, Delhi and western Uttar Pradesh. Although the amount is meagre, it is highly beneficial for rabi crops. The precipitation is in the form of snowfall in the lower Himalayas.
2. Central parts of India and northern parts of southern Peninsula also get winter rainfall occasionally.
3. Arunachal Pradesh and Assam in the northeastern parts of India also have rains between 25 mm and 50 mm during these winter months.
4. During October and November, northeast monsoon while crossing over the Bay of Bengal, picks up moisture and causes torrential rainfall over the Tamil Nadu coast, southern Andhra Pradesh, southeast Karnataka and southeast Kera

Question 21

The Hot Weather Season Temperature:

Answer 21

Temperature: With the apparent northward movement of the sun towards the Tropic of Cancer in March, temperatures start rising in north India. April, May and June are the months of summer in north India. In most parts of India, temperatures recorded are between 30°-32°C. In March, the highest day temperature of about 38°C occurs in the Deccan Plateau while in April, temperature ranging between 38°C and 43°C are found in Gujarat and Madhya Pradesh. In May, the heat belt moves further north, and in the north-western part of India, temperatures around 48°C are not uncommon .
The hot weather season in south India is mild and not so intense as found in north India. The Peninsular situation of south India with moderating effect of the oceans keeps the temperatures lower than that prevailing in north India.

Question 22

Some Famous Local Storms of Hot Weather Season

Answer 22

(i) Mango Shower : Towards the end of summer, there are pre-monsoon showers which are a common phenomena in Kerala and coastal areas of Karnataka. Locally, they are known as mango showers since they help in the early ripening of mangoes.
(ii) Blossom Shower : With this shower, coffee flowers blossom in Kerala and nearby areas.
(iii) 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”.
(iv) Loo : Hot, dry and oppressing winds blowing in the Northern plains from Punjab to Bihar with higher intensity between Delhi and Patna.

Question 23

Burst/ break of the monsoon

Answer 23

This sudden onset of the moisture-laden winds associated with violent thunder and lightening, is often termed as the “break” or “burst”.

Question 24

Monsoon branches why and what

Answer 24

As these winds approach the land, their southwesterly direction is modified by the relief and thermal low pressure over the northwest India. The monsoon approaches the landmass in two branches:
(i) The Arabian Sea branch (ii) The Bay of Bengal branch.

Question 25

Monsoon Winds of the Arabian Sea

Answer 25

The monsoon winds originating over the Arabian Sea further split into three branches:
(i) Its one branch is obstructed by the
Western Ghats. These winds climb the slopes of the Western Ghats from 900-1200 m. Soon, they become cool, and as a result, the windward side of the Sahyadris and Western Coastal Plain receive very heavy rainfall ranging between 250 cm and 400 cm. After crossing the Western Ghats, these winds descend and get heated up. This reduces humidity in the winds. As a result, these winds cause little rainfall east of the Western Ghats. This region of low rainfall is known as the rain-shadow area
(ii) Another branch of the Arabian sea monsoon strikes the coast north of Mumbai. Moving along the Narmada and Tapi river valleys, these winds cause rainfall in extensive areas of central India. The Chotanagpur plateau gets 15 cm rainfall from this part of the branch. Thereafter, they enter the Ganga plains and mingle with the Bay of Bengal branch
(iii) A third branch of this monsoon wind strikes the Saurashtra Peninsula and the Kachchh. It then passes over west Rajasthan and along the Aravallis, causing only a scanty rainfall. In Punjab and Haryana, it too joins the Bay of Bengal branch. These two branches, reinforced by each other, cause rains in the western Himalayas,

Question 26

Monsoon Winds of the Bay of Bengal

Answer 26

The Bay of Bengal branch strikes the coast of Myanmar and part of southeast Bangladesh. But the Arakan Hills along the coast of Myanmar deflect a big portion of this branch towards the Indian subcontinent. The monsoon, therefore, enters West Bengal and Bangladesh from south and southeast instead of from the south-westerly direction. From here, this branch splits into two under the influence of the Himalayas and the thermal low is northwest India. Its one branch moves westward along the Ganga plains reaching as far as the Punjab plains. The other branch moves up the Brahmaputra valley in the north and the northeast, causing widespread rains. Its sub-branch strikes the Garo and Khasi hills of Meghalaya. Mawsynram, located on the crest of Khasi hills, receives the highest average annual rainfall in the world.

Question 27

why the Tamil Nadu coast remains dry during this season. There are two factors responsible for it:

Answer 27

(i) The Tamil Nadu coast is situated parallel to the Bay of Bengal branch of southwest monsoon.
(ii) It lies in the rainshadow area of the Arabian Sea branch of the south-west monsoon.

Question 28

Season of Retreating Monsoon

Answer 28

The months of October and November are known for retreating monsoons. By the end of September, the southwest monsoon becomes weak as the low pressure trough of the Ganga plain starts moving southward in response to the southward march of the sun. The weather in the retreating monsoon is dry in north India but it is associated with rain in the eastern part of the Peninsula. Here, October and November are the rainiest months of the year.
The widespread rain in this season is associated with the passage of cyclonic depressions which originate over the Andaman Sea and manage to cross the eastern coast of the southern Peninsula. These tropical cyclones are very destructive

Question 29

October heat

Answer 29

Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive. This is commonly known as the ‘October heat’

Question 30

Distribution of Rainfall

Answer 30

The average annual rainfall in India is about 125 cm.
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.
Areas of Medium Rainfall : Rainfall between 100-200 cm is received in the southern parts of Gujarat, east Tamil Nadu, northeastern Peninsula covering Orissa, Jharkhand, Bihar, eastern Madhya Pradesh, northern Ganga plain along the sub-Himalayas and the Cachar Valley and Manipur.
Areas of Low Rainfall : Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau receive rainfall between 50-100 cm.
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.

Question 31

Variability of Rainfall

Answer 31

The values of coefficient of variation show the change from the mean values of rainfall. Dry areas have more.

Question 32

Climatic Regions of India According to Koeppen’s Scheme

Answer 32

Monsoon with short dry season- West coast of India south of Goa
Monsoon with dry summer- Coromandel coast of Tamil Nadu
Monsoon with dry winter- Ganga plain, eastern Rajasthan, northern Madhya Pradesh, most of North-east India
Cold humid winter with short summer- Arunachal Pradesh
Polar type- Jammu and Kashmir, Himachal Pradesh and Uttaranchal
Tropical savannah- Most of the Peninsular plateaus, south of the Tropic of Cancer
Semi-arid steppe climate- North-western Gujarat, some parts of western Rajasthan and Punjab
Hot desert- Extreme western Rajasthan

Question 33

Global Warming

Answer 33

The temperature of the world is significantly increasing. Carbon dioxide produced by human activities is a major source of concern. This gas, released to the atmosphere in large quantities by burning of fossil fuel, is increasing gradually. Other gases like methane, chlorofluorocarbons, and nitrous oxide which are present in much smaller concentrations in the atmosphere, together with carbon dioxide are known as green house gases. These gases are better absorbers of long wave radiations than carbon dioxide, and so, are more effective at enhancing the green house effect. These gases have been contributing to global warming. It is said that due to global warming the polar ice caps and mountain glaciers would melt and the amount of water in the oceans would increase.
The mean annual surface temperature of the earth in the past 150 years has increased. It is projected that by the year 2,100, global temperature will warm about 2°C. This rise in temperature will accompany many other changes: one of these is a rise in sea level, as glacier and sea
ice melt in response to warming. According to the current prediction, on an average, the sea level will rise 48 cm by the end of twenty first century. This would increase the incidence of annual flooding. Climatic change would promote insect-borne diseases like malaria, and lead to shift in climatic boundaries, making some regions wetter and others drier. Agricultural pattern would shift and human population as well as the ecosystem would experience change.