STD X – GEOG SUMMARY
CHAPTER 7 – CLIMATE
Syllabus
Climate:
Distribution of Temperature, Rainfall, Winds in Summer and Winter and factors affecting the climate
of the area. Monsoon and its mechanism.
Seasons: March to May – Summer, June to September – Monsoon; October to November – Retreating
Monsoon; December to February – Winter
❖ Climate: India has a tropical Monsoon Climate because India lies in the
tropical belt. Its climate is influenced by the monsoon winds which are largely
confined to the Tropics i.e., between 20°N and 20°S.
➢ Characteristics of Tropical Monsoon Climate:
(i) Relatively high temperatures
(ii) Dry winters
(iii) Alternation of seasons:
➢ Distribution of Temperature: Seasonal variations in temperature occur
from place to place and from region to region. Examples of variations in
temperature:
(i) Barmer in Rajasthan has temperatures up to 50°C while Dras in Kargil
has -40°C
(ii) The temperature touches -40°C in Kargil in the month of December,
whereas Kerala records 20°C or 22°C in the same month.
➢ Distribution of Rainfall: Variations not only occur in the type of
precipitation, but also in its amount and distribution: Examples of
variations in Precipitation:
(i) Mawsynram in Cherrapunji in Meghalaya receives 1100cm of rainfall
over the year, whereas Jaisalmer in Rajasthan hardly receives 9 cm of
rainfall in a year.
(ii) Most of India receives rainfall during June to September, but the coastal
areas of Tamil Nadu get rain in the beginning of the winter season.
➢ Factors Affecting the climate of the area: The various factors that affect
the climate of India are as follows:
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STD X – GEOG SUMMARY
(i) Latitude: India has vast latitudinal extent. It lies between 8*4’N and
37°6’N. Thus, there is a great distance of 3200 km north to south.
• The Tropic of Cancer divides India into two climatic zones. The
Northern half lies in the temperate zone & the Southern half lies in
the Tropical Zone.
(ii) Altitude – as we go higher and higher the temperature goes on
decreasing. For every 165 m increase in altitude, the temperature drops
by 1°C. This is known as lapse rate. So, places located at a higher
altitude are cooler than the plains which are at sea level.
(iii) Distance from the sea – Places near the sea experience moderating
influence of the sea have maritime climate. Places far away from the sea
have continental type of climate.
(iv) Himalayas – The Himalayas act as a climatic barrier. The Himalayas block
the bitter cold winds coming from central Asia and Siberia and protects
the Northern Plains from becoming extremely cold. The Himalayas also
block the South-West Monsoon Winds Arabian Sea Branch and force
them to rise, cool, condense and shed their moisture on the northern
plains.
(v) Influence of surrounding seas –
• These waterbodies act as a source of moisture to the South West
Monsoon Winds and the North-East Monsoon Winds.
• The seas have a moderating influence on the climate of the coastal
regions.
(vi) Varied Relief Features:
• The Western Ghats block the South-West Monsoon Winds Arabian
Sea Branch and give heavy rainfall to the Western coastal Plains
which lie on the windward side, whereas Deccan Plateau lies on the
leeward side and hence gets less rainfall.
• In Rajasthan the Aravalli’s lie parallel to the direction of the SouthWest monsoon Winds and hence do not block them. This makes
Rajasthan a dry area.
(vii) Monsoon Winds: Monsoons are periodic or seasonal winds. They
develop because of differential heating of land and sea.
[Date]
Hasmita Shah, B/203, Gokul Divine, Off S.V.Road, Irla, VIle Parle (West), Mumbai 400056.
Mob:9699926941
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STD X – GEOG SUMMARY
• The South-West Monsoon Winds Arabian Sea Branch and Bay of
Bengal Branch blow in summer.
• During winter, dry off-shore North-East Monsoon Winds blow and
bring rain to Tamil Nadu in winters.
(viii) Jet streams - Jet Streams are cold fast blowing winds that develop in the
upper layers of the atmosphere which determine the arrival and
departure of the rainfall.
(ix) Western Disturbances –These cyclones bring rain to Punjab & Haryana
which is beneficial to the crop of wheat, barley and mustard and
snowfall in Jammu and Kashmir in India.
(x) El-Nino Effect: El-Nino is a warm ocean current which sometimes
appears off the coast of Peru in South America during the month of
December.
➢ Seasons:
(i) The Hot and Dry Summer – March to May
(ii) The Hot and Wet Season – June to September
(iii) The Cool and dry Season – October to November
(iv) The Cold and dry Season – December to February
[Date]
Hasmita Shah, B/203, Gokul Divine, Off S.V.Road, Irla, VIle Parle (West), Mumbai 400056.
Mob:9699926941
3