2. Introduction
Climatic controls
Factors affecting India’s Climate
The Indian Monsoon
The Seasons
Distribution of rainfall
Monsoon as a unifying bond
CONTENTS
3. Climate refers to the sum total of
weather conditions over a large area for a
long period of time, generally taken for 30
years or more than that.
Elements of Climate-
Temperature Humidity Atmospheric
pressure
Wind Precipitation
4. There are mainly six factors affecting the
climate of any place-
1. Latitude
2. Altitude
4. Ocean Currents
5. Relief Features
6. Pressure and Wind System
7. Distance From The Sea
6. Latitude- Due to the curvature of the earth,
the amount of solar energy received varies
place to place according to the latitude. As a
result, air temperature generally decreases
from equator towards the poles.
Altitude- Due to the variation in altitude, the
higher ground of earth is less dense and
have less temperature. The hills are
therefore cooler during summer.
AFFECT OF
7. Pressure and Wind System- The pressure
and wind system of any area depends on the
latitude and altitude of the area. Therefore
it influences the temperature and rainfall
pattern.
Distance from the sea- As the distance from
the sea increases, its moderating influence
decreases and the people experience
extreme weather conditions. This system is
also called continentality.
AFFECT OF
8. Ocean Currents- Ocean currents along with
the onshore winds affect the climate
of the coastal region .
Relief Features- Relief plays an important
role in the determination of the climate of a
place. High mountains act as barriers for
cold and hot winds; the may also cause
precipitation if they are high enough and lie
in the path of rain-bearing winds. The
leeward side of the mountains remain
relatively dry.
AFFECT OF
10. Latitude- The tropic of cancer passes through
the middle of the country from the Rann
of Kuchchh in the west to Mizoram in the
east. Almost half of the country, lying
south of the Tropic of Cancer, belongs to
the tropical area. All the remaining area,
north of the Tropics, lies to the sub-tropics.
Therefore Indian climate has characteristics
of both tropical and subtropical climates
11. Altitude-
India has mountains to the north,
which have an average height of 6000
metres. India also has a vast coastal area
where the maximum elevation is about 30
metres. The Himalayas prevents the cold
winds from Central Asia from entering the
subcontinent. It is because of this
mountains that this subcontinent
experiences comparatively milder winters as
compared to the Central Asia.
12. Pressure and Wind System-
The climate of INDIA are governed
by the following atmospheric conditions-
• Pressure and surface
Winds
• Upper air circulation
• Western Cyclonic
Disturbances
13.
14. The climate of India is
strongly influenced by
the monsoon winds
therefore the climate of
India is termed as The
Indian Monsoon by the
Arabs who came sailing to
India. Monsoon meaning
season in Arabic is home
to a number of weather
conditions.
15. The Monsoon Period
The monsoon are experienced in the
tropical area roughly between 20°𝑁 and
20°𝑆. To understand this we have to first
learn about the following:
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
16. The shift of the position of Inter Tropical
convergence
zone (ITCZ) in summer,
over the Ganga plain
(this is equatorial
trough normally
positioned between 5°𝑁
of the equator. It is also
known as the monsoon trough during the
monsoon season).
17. 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 affects the Indian monsoon.
The Tibetan plateau gets intensely
heated during summer, which results into
strong vertical air currents and the
formation of low pressure over the
plateau at about 9 km above the sea level.
18. The movement of
the westerly jet
stream to the
Himalayas and the
presence of the
tropical easterly
jet stream over
the Indian peninsula
during summer.
19. The Onset Of The Monsoon
The Monsoon, unlike the trades, are not
steady winds but are pulsating in nature,
affected by different atmospheric
conditions encountered by it, on its way
over the warm tropical seas. The
duration of the monsoon is between 100
to 120 days from early June to mid-
September. Around the time of its
arrival, the normal rainfall increases
suddenly and continues constantly for
several days. This is known as the ‘burst’
of the monsoon, and can be distinguished
from the pre monsoon showers.
20. Withdrawal of the monsoon
Withdrawal of the monsoon is a more
gradual process. The withdrawal of the
monsoon begins in northwestern states of
India by early September. By mid-
October, it withdraws completely from
the northern half of the peninsula. The
withdrawal from the southern half is
fairly rapid. By early December, the
monsoon has withdrawn from the rest of
the country.
21. The Monsoon type climate of India is
characterized by a distinct seasonal
pattern. The weather
conditions greatly
changes from season
to season. Four main
Seasons are there in
India- Cold weather Summer Rainy
Season, Hot weather season, the
advancing monsoon and the retreating
monsoon.
THE SEASONS
22. The cold weather season
begins from mid-November in
northern India and stays till
February. December and
January are the coldest
months in the northern part
of India. The temperature decreases from south
to north. Days are warmer than the nights. Frost
is common in the north and higher slopes of the
Himalayas experience snowfall. During this season
the northeast trade winds prevail over the
country. They blow from land to sea, hence, it is
a dry season.
COLD WEATHER SEASON
23. The hot weather season in India begins from the
month of March and carried away till May. The
summer months experience
Rising temperature and falling
Air pressure in the northern
Part of the country. Towards
the end of May, an elongated
Low-pressure area develops in the region extending
from the Thar Desert in the Northwest to Patna
and Chotanagpur plateau in the east and southeast.
Circulation of air begins to set in around this trough.
HOT WEATHER SEASON
24. ADVANCING MONSOON
The inflow of the south west
monsoon into India by June brings
about a total change in the weather.
Early in the season, the windward
side of the western Ghats receives
very heavy rainfall. The maximum
rainfall of this season is received in the
northeastern India, mainly in Mawsynram in the
southern ranges of the Khasi Hills, which is also the
highest average rainfall in the world. Rainfall in the
Ganga valley decreases from east to west.
25. During October-November, with
the apparent movement of the sun
towards the south, the monsoon
trough over the northern plains
becomes weaker. This is gradually
replaced by a high pressure
System. The south west monsoon winds weaken and
start withdrawing gradually. By the beginning of
October, the monsoon withdraws from the
Northern plains. The low pressure conditions get
transferred towards the Bay of Bengal. This
results into the heavy rainfall in the southern part.
RETREATING MONSOON
26. Parts of western coast and northeastern
India receive over about 400
cm of rainfall annually.
However, it is less than 60
cm in Western Rajasthan and
adjoining part of Gujarat,
Haryana and Punjab. Rainfall
is equally low in the interior of the Deccan
plateau, and the east of the Sahayadris.
DISTRIBUTION OF RAINFALL
27. A third region of low
precipitation is the region
of Ladhakh in Jammu and
Kashmir.
The rest of the
country experiences moderate amount of
rainfall. Snowfall is restricted to the
Himalayan region. Owing to the nature of
monsoons, the annual rainfall is highly
variable from year to year.
28. The Himalayas protect the subcontinent from
the Siberian air. This enables
the northern India to have
uniformly higher temperatures
as compared to other areas on
the same latitudes. The peninsular plateau, under
the influence of the sea from three sides, has
moderate temperatures. Despite such
moderating influences, there are great variations
in the temperature conditions. The unifying
influence of the monsoon is quite perceptible.
MONSOON-AS A UNIFYING BOND
