2. THE CLIMATIC VARIATIONS
Climate is a measure of the average pattern of variation
in temperature, humidity, atmospheric
pressure, wind, precipitation, atmospheric particle count and
other meteorological variables in a given region over long
periods of time.
Climate is different from weather, in that weather only
describes the short-term conditions of these variables in a
given region. India has 'Tropical Monsoon' type of climate.
The word monsoon has been derived from the Arabic word
'Mausim' means season. Monsoon refers to the seasonal
reversal in the wind direction during a year .The whole of
India has a tropical monsoonal climate, since the greater part
of the country lies within the trophies, and the climate is
influenced by the monsoons.
3. In summer the temperature of some parts of Rajasthan
desert is 50 degree C. Whereas it may be 20 degree C in
Pahalgam in Jammu & Kashmir. On a winter night,
temperature at Drass in Jammu & Kashmir may be as low
as -45 degree. Tiruvanantapuram, on the other hand, may
have a temperature of 22 degree C. The position of the
mountain ranges and direction of the rain-bearing winds are
the two main factors that determine the climate of India .
Alternating seasons is the chief characteristic of India's
Climate. There are variations not only in the form and types
of precipitation but also in its amount and the seasonal
distribution Precipitation is mostly in the form of snowfall in
the upper parts of Himalayas, it rains over the rest of the
country. The annual precipitation varies from over 400 cm in
Mawsynram in Meghalaya to less than 10 cm in Ladakh and
5. Latitudinal Extent:The latitudinal extent (from about 8 °N to 37 °N) is an
important factor which influences the climatic conditions of this region. The
southern half of India lies in the tropical belt close to the Equator, and is
surrounded by water bodies.The northern half which is above the Tropic of
Cancer lies in the temperate belt. This part is not only away from the
Equator, but also away from the moderating influence of the water bodies.
These two parts of India enjoy different climatic conditions due to their
location and latitudinal extent.
Location of the Himalayas and Western and Eastern
Ghats: Relief forms an important factor that affects the climate of India.
The high Himalayan Mountain in the north act as a barrier to the south-west
monsoon winds forcing the winds to shed most of its rainfall in India before
crossing the Himalayas. The cold winds in winter from Central Asia are
mainly obstructed from coming into India by these high Himalayas. So the
severity of winter in India is not that intense. The Western and Eastern
Ghats on either side of the Peninsular in South India force the monsoon
winds to give plenty of rainfall in the coastal regions. Again, the eastern
slopes of the Western Ghats fall in the rain-shadow area as the Western
Ghat obstructs the monsoon winds and get heavy rainfall on the western
slopes. .
Impact of Prevailing Winds:The monsoons are the prevailing winds
over the whole of India. These winds are a unique feature of the climate of
India. During the summer season, the monsoon wind covers the entire India
and brings rainfall to practically every part of the country.
6. Altitude: Temperature decreases with increase in height at the rate of 6.5°C
per 1000 meters difference in height. The high peaks of the Himalayas are thus
always covered by snow. Shimla is therefore cooler than Delhi as it lies at a
higher elevation. Ooty in the Nilgiris in the Western Ghats is cool even in
summer because of its height though it lies near the equator.
Influence of the Water Bodies:The water bodies surrounding India, i.e. The
Indian Ocean, the Bay of Bengal and the Arabian Sea, exert moderating
influence on the climatic conditions. These water bodies provide much needed
moisture to the summer monsoons, which provide heavy rainfall. Moreover, the
climate of the coastal areas is also modified by the influence of these water
bodies.The places which are in the interior experience continental climate, as
they are far away from the moderating influence of the water bodies. Thus, such
places experience very hot summer and cold dry winters. In contrast the coastal
areas enjoy almost the same type of climatic conditions throughout the years.
12. SEASONS
The climate of India may be described as tropical
monsoon. Even northern India, lying beyond the tropical
zone, acquires a tropical touch marked by the relatively
high temperatures. The large size of the country and its
varied relief play a crucial role in determining the climatic
variations in different part of India. But the seasonal
rhythm of the monsoon is apparent throughout India. It
may conveniently from the basis for dividing the year into
different seasons. The most characteristic feature of the
monsoon is the complete reversal of winds. It eventually
leads to the alternation of seasons. India is known as the
"land of the endless growing season". The year is divided
into fours seasons :Winter, Summer ,Advancing Monsoon
and Retreating Monsoon
13. WINTER
The winter season begins from mid-November and stays till February in
northern India. December and January are the coldest months in the
northern part of India. The temperature ranges between 10°-15°C in the
northern plains, while it ranges between 24°-25°C in Chennai. The
northeast trade winds prevail over the country in this season. As these
winds blow from land to sea, most parts of the country experience a dry
season. The inflow of the cyclonic disturbances from the west and the
northwest is a characteristic feature of the cold weather over the
northern plains. These low-pressure systems originate over the
Mediterranean Sea and Western Asia and move into India. They cause
winter rains over the plains and snowfall in the mountains. The winter
rainfall is in small amount but is very important for the rabi crop in the
north western India . This rainfall is locally known as mahawat The
peninsular region does not get a well-defined winter because of the
moderating influence of the sea.
17. SUMMER
The summer season is from March to May. During this period, the global
heat belt shifts towards north because of the apparent northward movement
of the sun. During summer, the temperatures rise and air pressure falls in
the northern part of the country. In March, the highest day temperatures of
about 38 degree C occur in the Deccan Plateau. Therefore, Peninsular
India places south of Satpuras experience temperature between 26-32
degree C. Central India, comprising of Delhi and Madhya Pradesh
experience temperature between 40-45 degree C . North-West India,
comprising mainly of Rajasthan has very high temperature more than 45
degree C, due also to features like sandy soil, direct insulation and lack of
cloud cover. Towards the end of May, an elongated low-pressure area
develops in the region which extends from the Thar Desert in the northwest
to Patna and Chota Nagpur Plateau in the east and southeast . The low
pressure systems that originate over the eastern Mediterranean region in
winter and move eastwards towards India passing over Iran, Afghanistan
and Pakistan are responsible for the winter rain in northern India .These
cyclones contribute to the bulk of the rainfall of the Coromandel Coast.
18. SUMMER-LOCAL STORMS
Mango Showers (since the rain showers are good for the
mango trees) occurs along the coast of Kerala
.Kalbaisakhi in the month of Baisakh occurs in Assam
and West Bengal. These are thunderstorms,
accompanied with strong winds are heavy rainfall. This is
good for the tea crop in Assam and the jute and rice in
West Bengal. In Assam these storms are called Bardoli
chherha .Loo is the name given to the hot, dry winds that
blow in the Northern Plains. It is very common in Punjab,
Haryana, Western Uttar Pradesh (called “Aandhi") and
Bihar. Blossom Shower with this shower, coffee flowers
blossom in Karnataka and its nearby areas.
22. ADVANCING MONSOON
The rainy season begins from early June. The low-pressure condition over the
northern plains intensifies at this time. It attracts the trade winds from the
southern hemisphere. These south-east trade winds cross the equator and blow
in a south-westerly direction to enter the Indian peninsula as the south-west
monsoon winds. These winds bring abundant moisture to the subcontinent.
These winds blow at an average velocity of 30 km/h. The monsoon winds cover
the country in about a month; barring the extreme north-west .The windward
side of the Western Ghats receives very heavy rainfall, early in the rainy season.
The Deccan Plateau and parts of Madhya Pradesh also receive some rain, in
spite of lying in the rain shadow area. The north-eastern part of the country
receives the maximum rainfall of this season. Mawsynram (Meghalaya) receives
the highest average rainfall in the world. Rainfall in the Ganga valley decreases
from east to west. Rajasthan and parts of Gujarat get scanty rainfall. The
monsoon is famous for its uncertainties. It may cause heavy floods in one part of
the country, and may be responsible for droughts in other part. Because of its
uncertain behaviour, it sometimes disturbs the farming schedule in India. This
affects millions of farmers all over the country.
23.
24. RETREATING MONSOON
During October to November, the sun apparently moves
towards the south. During this period, the monsoon over the
northern plains becomes weaker. The south-west monsoon
winds weaken and start withdrawing gradually. The monsoon
withdraws from the northern plains by the beginning of
October. The retreat of the monsoon is marked by clear skies
and rise in temperature. While day temperatures are high,
nights are cool and pleasant. Humidity is still present. High
temperature and humidity, makes the weather quite
uncomfortable during the day. This is commonly known as
“October Heat”. The temperature begins to fall rapidly in
northern India by the second half of October. The low-
pressure conditions over north western India move to the Bay
of Bengal by early November. This shift leads to cyclonic
depressions over the Andaman Sea. These cyclones usually
cross the eastern coasts of India and cause heavy and
widespread rain. These cyclones may also arrive at the
Coasts of Orissa, West Bengal and Bangladesh.
25.
26. Difference between the Retreating S.W. Monsoon
and North East Monsoon
They blow during the months of
October to November
They blow during the months of
January to mid March.
This is a season of transition between
the hot, rainy season and the cold, dry
season
This is the cold weather season
Characterised by oppressive head and
humidity known as "October Heat"
This is a very pleasant season with
low temperatures, low humidity, clear
skies
They blow in the S.W. direction but are
not strong enough to blow right into the
Northern Plain.
These winds blow in N.E direction
from the land to the sea.
The withdraw in stages which results They do not give rain.
27. IMPORTANCE OF MONSOONS
Rains are also important as they give respite to
people after summers. Rains are also important for
India as they help in maintaining the ecology and bio
diversity of nature. Himalayan forests are completely
dependent on rainfall as there is shortage of ground
water in hilly areas. Though there are lakes in the hills,
they too need to be recharged, for which they depend
on monsoon showers. As 60% of India's economy
depends on agriculture sector that provides
employment to lacks of farmers, who in turn produce
food grains for millions of people of our country. Steps
should be taken to address the problems of global
warming and deforestation. If proper efforts are made
for water, soil and forest conservation, surely it would
result in increased rains during monsoons which is a
must for agriculture economy in India these days.
28. THE RAINFALL DISTRIBUTION
The distribution of rainfall surface of the Earth and the direction in any
region is mostly influenced by the relief features on the of the rain-bearing
winds in that region. Another important factor which influences the
distribution of annual rainfall in India is the path followed by the cyclonic
depressions. The region located on the windward side of mountains, hills or
plateaus receives comparatively more rainfall than the leeward side.
The average annual rainfall in India is about 120 cm. Most of this rainfall is
received during four months (June, July, August and September) of the
Southwest Monsoon season. The amount of annual rainfall varies not only
from place to place, but also from season to season. In general, the
monsoon rainfall is highly erratic.
Many areas of the north-eastern part of India receive more than 500 cm of
annual rainfall, while many parts in the Thar Desert receive less than 10 cm
of annual rainfall. There are yearly variations in the distribution of annual
rainfall and they are the root cause of floods, droughts and famines in India.
Broadly, India can be divided into the following four regions, depending upon
the average annual rainfall received by those regions.
29. Areas of Very Heavy Rainfall:
The areas receiving an average rainfall of more than 200 cm are
included in this region. The highest rainfall occurs along the Western
Coastal plain, extending from Mumbai to Thiruvananthapuram, the
western slopes of the Western Ghats, the southern slopes of the
Eastern Himalayas, the sub-Himalayan areas in the northeast, the
hills of Meghalaya. In certain parts of the Khasi and Jaintia Hills, in
north-eastern India, the average annual rainfall generally exceeds
1000 cm, but drops to about 200 cm or even less in the
Brahmaputra valley and the adjoining hills, which are located in the
rain-shadow area. Meghalaya is the wettest part of India with
Mawsynram and Cherrapunji getting about 1220 cm and 1100 cm of
average annual rainfall respectively. This region does not
experience drought conditions, but is subjected to frequent floods.
Areas of Heavy Rainfall:
The areas receiving an average annual rainfall between 100 cm
and 200 cm are included in this region. The eastern slopes of the
Western Ghats, northern and middle Ganga valley, north-eastern
peninsula, Manipur, coastal areas of Andhra Pradesh and Tamil
Nadu are included in this region. Here irrigation is needed as a
protective measure against drought.
30. Areas of Low Rainfall:
The areas receiving an average annual rainfall between 50 cm and 100
cm are included in this region. The Upper Ganga Valley, eastern
Rajasthan, Punjab, Haryajia, Kashmir and large parts of Gujarat,
Maharashtra, Western Madhya Pradesh, Andhra Pradesh, Karnataka,
and Tamil Nadu, are included in this region. Large irrigation projects
have been developed to overcome the danger of droughts and famines.
Areas of Very Low Rainfall:
The areas receiving an average annual rainfall of less than 50 cm are
included in this region. Here the desert and semi- desert conditions
prevail. The areas included are the rain-shadow areas in the Deccan
Plateau, north Kashmir, southern Punjab, western Rajasthan and
Kachchh. There is an acute shortage of water in these areas.
31.
32.
33. NATURAL VEGETATION
We see a variety of plant life in our surroundings. How nice it is
to play in field with green grasses. There are also small plants
called bushes and shrubs like cactus and flowering plants etc.
Besides there are many tall trees some with many branches and
leaves like neem, mango or some which stand with few leaves
such as palm. The grasses, shrubs and trees, which grow on their
own without interference or help from human beings are called
natural vegetation. Do you wonder how these differ from each
other. Different types of natural vegetation are dependent on
different climatic conditions, among which the amount of rainfall is
very important. Due to varied climatic conditions, India has a wide
range of natural vegetation. Vegetation of India can be divided
into five types – Tropical evergreen forest, Tropical deciduous
forest, Thorny bushes, Mountain vegetation and Mangrove
forests.
34.
35.
36. These forests are restricted to heavy rainfall areas of the
Western Ghats and the island groups of Lakshadweep, Andaman
and Nicobar, upper parts of Assam and Tamil Nadu coast. They
are at their best in areas having more than 200 cm of rainfall with
a short dry season. The trees reach great heights up to 60 meters
or even above. Since the region is warm and wet throughout the
year, it has a luxuriant vegetation of all kinds – trees, shrubs, and
creepers giving it a multilayered structure. There is no definite
time for trees to shed their leaves. As such, these forests appear
green all the year-round. Some of the commercially important
trees ofth is forest are ebony, mahogany, rosewood, rubber and
cinchona. The common animals found in these forests are
elephants, monkey, lemur and deer. The one horned rhinoceros
are found in the jungles of Assam and West Bengal. Besides
these animals plenty of birds, bats, sloth, scorpions and snails are
also found in these jungles.
37.
38. These are the most widespread forests of India. They are also called
the monsoon forests and spread over the region receiving rainfall
between 200 cm and 70 cm. Trees of this forest-type shed their leaves
for about six to eight weeks in dry summer. On the basis of the
availability of water, these forests are further divided into moist and dry
deciduous. The former is found in areas receiving rainfall between 200
and 100 cm. These forests exist, therefore, mostly in the eastern part of
the country – northeastern states, along the foothills of the Himalayas,
Jharkhand, West Orissa and Chhattisgarh, and on the eastern slopes of
the Western Ghats. The dry deciduous forests are found in areas
having rainfall between 100 cm and 70 cm. These forests are found in
the rainier parts of the peninsular plateau and the plains of Bihar and
Uttar Pradesh. Some of the commercially important trees of the forest
are Teak, Sal, Peepal, Neem grow. A large part of this region has been
cleared for cultivation and some parts are used for grazing. In these
forests, the common animals found are lion, tiger, pig, deer and
elephant.
39.
40. In regions with less than 70 cm of rainfall, the natural
vegetation consists of thorny trees and bushes. This type
of vegetation is found in the north-western part of the
country including semi-arid areas of Gujarat, Rajasthan,
Madhya Pradesh, Chhattisgarh, Uttar Pradesh and
Haryana. Trees are scattered and have long roots
penetrating deep into the soil in order to get moisture. The
stems are succulent to conserve water. Leaves are
mostly thick and small to minimize evaporation. These
forests give way to thorn forests and scrubs in arid areas.
Some of the commercially important trees of the forest
are Acacias, palms, euphorbia's and cacti. In these
forests, the common animals are rats, mice, rabbits, fox,
wolf, tiger, lion, wild ass, horses and camels.
41.
42. In mountainous areas, the decrease in temperature with
increasing altitude leads to the corresponding change in natural
vegetation.The wet temperate type of forests are found between
a height of 1000 and 2000 meters. Evergreen broad-leaf trees
such as oaks and chestnuts predominate. Between 1500 and
3000 meters, temperate forests containing coniferous trees.
These forests cover mostly the southern slopes of the Himalayas,
places having high altitude in southern and north-east India. At
higher elevations, temperate grasslands are common.These are
used extensively for grazing by nomadic tribes like the Gujjars
and the Bakarwals. At higher altitudes, mosses and lichens form
part of tundra vegetation. The common animals found in these
forests are Kashmir stag, spotted dear, wild sheep, jack rabbit,
Tibetan antelope, yak, snow leopard, squirrels, Shaggy horn wild
ibex, bear and rare red panda, sheep and goats. Some of the
commercially important trees of the forest are pine, deodar, silver
fir, spruce and cedar.
43.
44. The mangrove or tidal forests are found in the areas of
coasts influenced by tides. Mud and silt get accumulated
on such coasts. Dense mangroves are the common
varieties with roots of the plants submerged under water.
The deltas of the Ganga, the Mahanadi, the Krishna, the
Godavari and the Kaveri are covered by such vegetation.
In the Ganga-Brahamaputra delta, sundari trees are
found, which provide durable hard timber. Royal Bengal
Tiger is the famous animal in these forests. Turtles,
crocodiles, gharials and snakes are also found in these
forests. Some of the commercially important trees of the
forest are Palm, coconut, keora, agar & sundari trees.
The common animals found in these forests are tigers
,turtles, crocodiles, gharials and snakes.
45. Forests are very useful for us. They perform various
functions. Plants release oxygen that we breathe and
absorb carbon dioxide. The roots of the plants bind the
soil; thus, they control soil erosion. Forests provide us with
timber for furniture, fuel wood, fodder, medicinal plants and
herbs, lac, honey, gum, etc. Forests are the natural habitat
of wild life. Natural vegetation has been destroyed to a
large extent because of the reckless cutting of trees. We
should plant more trees and protect the existing ones and
make people aware of the importance of trees. We can
have special programmes like Van Mahotsav to involve
more people in making our earth green.
47. Forests are home to a variety of wild life. There are thousands of
species of animals and a large variety of reptiles, amphibians,
mammals, birds, insects and worms which dwell in the forest.
The tiger is our national animal. It is found in various parts of the
country. Gir forest in Gujarat is the home of Asiatic lions. Elephants
and one-horned rhinoceroses roam in the forests of Assam.
Elephants are also found in Kerala and Karnataka. Camels and wild
asses are found in the Great Indian desert and the Rann of Kuchchh
respectively. Wild goats, snow leopards, bears, etc. are found in the
Himalayan region. Besides these, many other animals are found in
our country such as monkey, wolf, jackal, nilgai, cheetal, etc.
India is equally rich in bird life. The peacock is our national bird.
Other common birds are parrots, pigeons, mynah, geese, bulbul and
ducks. There are several bird sanctuaries which have been created
to give birds their natural habitat. These provide the birds protection
from hunters.
48. Some birds such as the Pelican, Siberian Crane , Stork, Flamingo,
Pintail Duck and Curlew migrate to our country in the winter season
every year. Siberian Cranes migrate from Siberia. They arrive in
December and stay till early March.
There are several hundreds of species of snakes found in India. Cobras
and kraits are important among them.
49. Due to cutting of forests and hunting, several species of wildlife of
India are declining rapidly. Many species have already become
extinct. In order to protect them many national parks, sanctuaries
and biosphere reserves have been set up. The Government has
also started Project Tiger and Project Elephant to protect these
animals.
We can also contribute in conserving wildlife. You can refuse to
buy things made from parts of the bodies of animals such as their
bones, horns, fur, skins and feathers. Every year we observe wildlife
week in the first week of October, to create awareness of conserving
the habitats of the animal kingdom.
