இந்தக் கட்டுரையில், TNPSC குரூப் 1, குரூப் 2, குரூப் 2A, குரூப் 4 மாநிலப் போட்டித் தேர்வுகளான TNUSRB, TRB, TET, TNEB போன்றவற்றுக்கான முறைகள் இலவசக் குறிப்புகளைப் பெறுவீர்கள்.தேர்வுக்கு தயாராவோர் இங்குள்ள பாடக்குறிப்புகளை படித்து பயன்பெற வாழ்த்துகிறோம்.
Climate
The factors affecting the Climate
Latitude
Latitudinally, India lies between 8°4’N and 37°6’N latitudes.
The Tropic of cancer divides the country into two equal halves. The area located to the
south of Tropic of cancer experiences high temperature and no severe cold season
throughout the year whereas, the areas to the north of this parallel enjoys sub- tropical
climate.
Altitude
When the altitude increases, the temperature decreases. Temperature decreases at the
rate of 6.5 0 C for every 1000 metres of ascent. It is called normal lapse rate.
Hence, places in the mountains are cooler than the places on the plains.
Distance from the Sea
A large area of India, especially the peninsular region, is not very far from the sea and
this entire area has a clear maritime influence on climate.
The regions of Central and North India have seasonal variations in temperature due to
the lack of dominance of the oceans.
The coastal areas are very humid and have high rainfall potential. Here, summers are
hot and winters are cold.
Due to this fact, the amount of rainfall at Kolkata located near the coast is 119 cm and it
decreases to just 24 cm at Bikaner which is located in the interior part.
Monsoon Wind
These are seasonal reversal winds and India remains in the influence of these winds for
a considerable part of a year.
Southwest monsoon brings down the temperature of the entire India and causes
moderate to heavy rainfall in many parts of the country. Similarly, the climate of
southeast India is also influenced by northeast monsoon.
Equable climate is also called as the British climate, which is neither too hot nor too
cold.
Weather refers to the state of atmosphere of a place at a given point of time.
Climate is the accumulation of daily and seasonal weather events of a given location
over a period of 30-35 years.
Relief
The Himalayas acts as a barrier to the freezing cold wind blows from central Asia and
keep the Indian subcontinentwarm. As such the north India experiences tropical climate
even during winter.
During this season, Mangalore, located on the coast gets the rainfall of about 280 cm
whereas the Bengaluru located on the leeward side receives only about 50 cm rainfall.
Jet Streams
Jet streams are the fast moving winds blowing in a narrow zone in the upper
atmosphere.
According to the Jet stream theory, the onset of southwest monsoon is driven by the
shift of the sub tropical westerly jet from the plains of India towards the Tibetan
plateau.
Monsoon
The word ‘monsoon’ has been derived from the Arabic word ‘Mausim’ which means
‘season’.
It blows from the south-west to north-east during summer and from the north- east to
south-west during winter.
Such systematic change in the direction of planetary winds is known as monsoon.
Seasons: The meteorologists recognize the four distinct seasons in India.
They are;
Winter Season (January – February).
Summer Season (March – May).
Southwest monsoon or Rainy Season (June – September).
Northeast monsoon Season (October – December).
Winter season
During this period, the vertical rays of the Sunfalls over tropic of capricorn which is far
away from India.
Hence, India receives the slanting sun’s rays which results in low temperature.
The cold weather season is characterized by clear skies, fine weather, light northerly
winds, low humidity and large day time variations of temperature.
The rain during this season generally occurs over the Western Himalayas, Tamil Nadu
and Kerala.
This rainfall is very useful for the cultivation of winter wheat.
Summer season
During this season, the vertical rays of the Sunfalls over the peninsular India.
Hence, there is a steady increase in temperature from south to north.
Weather over the land areas of the country is influenced by thunderstorms associated
with rain and sometimes with hail mostly in the middle and later part.
During this season, temperature starts increasing all over the country and by April, the
interior parts of south India record mean daily temperatures of 30°C -35°C.
Mango Showers – They bring pre monsoon showers to the west coast during the month
of May.There are few thunder showers called “Mango Showers” which helps in quick
ripening of mangoes along the coast of Kerala and Karnataka.
“Norwesters” or “Kalbaisakhis” are the local storms with thunder that blow from north
western part and rain lasting for short durations.
It occurs over the eastern and north eastern parts over Bihar, West Bengal and Assam
during April and May.
Southwest monsoon
The southwest monsoon is the most significant feature of the Indian climate.
The Onset of the southwest monsoon takes place normally over the southern tip of the
country by the first week of June, advances along the Konkan coast in early June and
covers the whole country by 15th July.
The monsoon is influenced by global phenomenon like ElNino.
Prior to the onset of the southwest monsoon, the temperature in north India reaches
upto 46°C.
Burst of monsoon’: The sudden approach of monsoon wind over south India with
lightning and thunder is termed as the ‘break’ or ‘burst of monsoon’.
Kerala is the first state to receive rainfall from the south west monsoon in India
The monsoon wind strikes against the southern tip of Indian land mass and gets divided
into two branches.
Arabian sea branch
Bay of Bengal branch
1. Arabian Sea branch
The Arabian Sea branch of southwest monsoon gives heavy rainfall to the west coast of
India as it is located in the windward side of the Western Ghats.
The other part which advances towards north is obstructed by Himalayan Mountains
and results in heavy rainfall in north.
As Aravalli Mountain is located parallel to the wind direction, Rajasthan and western
part do not get much rainfall from this branch.
2. The Bay of Bengal branch
The Bay of Bengal branch moves towards northeast India and Myanmar.
This wind is trapped by a chain of mountains namely Garo, Khasi and Jaintia are mainly
responsible for the heaviest rainfall caused at Mawsynram located in Meghalaya.
Later on, this wind travel towards west which results in decrease in rainfall from east to
west.
Over all about 75% of Indian rainfall is received from this monsoon
Northeast monsoon season
During winter the Indian Subcontinent becomes colder than the Indian Ocean.
As a result the wind blows from Northeast to South West direction.
This is dry wind system and it does not produce rainfall in the coastal region of south
Asia except the Coromandel Coast of India and Sri Lanka.
This is known as North East Monsoon or Retreating Monsoon in South Asia.
The southwest monsoon begins to retreat from north India by the end of September
due to the southward shifting pressure belts. The southwest monsoon wind returns
from Indian landmass and blows towards Bay of Bengal.
The Coriolis force deflects this wind and makes it to blow from northeast. Hence, it is
known as Northeast monsoon or Post-monsoon season.
The season is associated with the establishment of the north-easterly wind system over
the Indian subcontinent.
Andhra Pradesh, Tamilnadu, Kerala and south interior Karnataka receive good amount
of rainfall accounting for 35% of their annual total.
Many parts of Tamil nadu and some parts of Andhra Pradesh and Karnataka receive
rainfall during this season due to the storms forming in the Bay of Bengal.
Large scale losses to life and property occur due to heavy rainfall, strong winds and
storm surge in the oastal regions.
The day time temperatures start falling sharply all over the country.
Agriculture in India mostly depends on the rainfall brought by the monsoons.
During the El Nino year the temperature of the ocean water increases.
This weakens the high pressure over Indian Ocean thereby reduces the strength of
south west monsoon over south Asia.
However during winter, it induces the low pressure over the ocean resulting in severe
depressions and cyclones.
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