INDIA-CLIMATE
Why India has a tropical monsoon type of climate?
India’s tropical monsoon climate is primarily influenced by the following factors: -
1) Geographical loca on: -
India lies predominantly between the Tropic of cancer and the equator placing it
within the tropical zone. This geographical loca on exposes the country to
abandon solar radia on throughout the year, leading to high temperatures.
2) Monsoon winds: - The seasonal reversal of winds known as the monsoon wind is
a defining characteris c of Indias climate.
Summer Monsoon: - During summer, the Indian landmass heats up
rapidly crea ng a low- pressure area this draws moisture laden winds
from the Indian Ocean and the Bay of Bengal resul ng in heavy rainfall
across the country.
Winter monsoon: - In winters the landmass cools down and a high-
pressure area develops. This leads to a dry cold wind blowing from the
land towards the sea.
3) The Himalayas: - The Himalayan Mountain Range acts as a barrier preven ng
cold dry winds from Central Asia from entering the Indian subcon nent this helps
in retaining heat and moisture influencing the monsoon system.
4) Tibetan plateau: - The Tibetan plateau heats up during summer, crea ng a low-
pressure area. Slow pressure system further intensifies the monsoon winds
drawing moisture laden air from the Indian Ocean.
5) Inter- Tropical convergence zone: - The ITCZ a belt of low pressure near the
equator shi s northward during the summer monsoon bringing rainfall to India.
These factors collec vely contribute to India’s tropical monsoon climate
characterised by dis nct seasons heavy rainfall during the monsoon and a dry
winter season. This clima c pa ern significantly impacts during agriculture,
economy and overall environment.
THE CYCLE OF SEASONS: -
The cold weather season: -
Dura on and characteris cs
The cold weather season, or winter season, in India starts from mid-November to
mid-March.
Temperature is generally low across the country.
North-South Temperature gradient: Generally, temperature decreases from
south to north. In the Himalayas the temperature drops below freezing
point in some places. The plains also experience cool weather in contrast
southern India remains rela vely warmer due to its proximity to the ocean.
The mean temperature in the Northern part of India is below 20° C while in
southern part it is above 20 °C. The days are generally warmer while the
nights are cold. January and February are the coldest month in the in many
parts of India.
Major part of India remains dry only coromandel coast in Tamil Nadu
receives winter rainfall because of retrea ng north-east monsoon winds.
High Pressure develops over north- west as the temperature is low so the
weather is pleasant and sky is clear, low humidity and cool winds.
Western disturbance: Western disturbances, origina ng from the
Mediterranean region bring rainfall and snowfall to the northwestern parts
of India, especially affec ng states like Punjab Himachal Pradesh and
Jammu and Kashmir.
1. What is Western Disturbance?
Western disturbance are low-pressure weather systems that
originate in the Mediterranean Sea and move eastward across Asia
towards the Indian subcon nent. They are also known as
Extratropical cyclones or mid la tude cyclones. They are primarily
responsible for bringing rain and snowfall to northern India during
the winter season the key impact of western disturbance on India
include
Rainfall and snowfall
Agriculture benefits
Water resources
Temperature drop
Fog forma on
The Hot Weather Season
Dura on and characteris cs
Starts from mid-March and con nues ll the end of May.
Temperatures start rising in March and peak in May and early June.
Northern Plains experience very high temperatures. When
exceeding 40 °C.
The coastal regions have compara vely moderate temperatures due
to cooling effect of the sea.
Heat waves: Northern and Central India o en experience intense
hot, dry, dust-laden winds locally waves, known as loo. Especially in
places like Rajasthan (exceeding 48°C) Delhi and Madhya Pradesh.
Onset of monsoon winds: Towards the end of May the southwest
monsoon wind starts building up in the Indian Ocean and move
towards the Indian subcon nent bringing relief from the heat.
Pre monsoon showers: some regions experience pre monsoon
showers before the monsoon season officially starts
Mango Showers: In Kerala & Karnataka, these showers are
called mango showers as they help in ripening of the
mangoes.
Kal Baisakhi: In West Bengal Orissa and Assam these are
sudden violent thunderstorm with rain, locally known as Kal
Baisakhi which helps cool down the temperature and are
beneficial for crops like jute and rice.
The South-West Monsoon Winds
Dura on and characteris cs
Start from June and con nue ll the end of September.
It begins with the Southwest monsoon winds which arrive on the
Indian mainland by early June star ng in Kerala and then spreads
northward across the country within four to five weeks.
Due to excessive heat during the summer, the land mass of India is
heated and thus a low-pressure area develops over it. On the other
hand, the surrounding water bodies remain rela vely cool and a
high-pressure area develops over them.
The low-pressure area over the land masses is intense enough to
a ract the southeast trade winds from the Southern Hemisphere.
A er crossing the equator these winds get deflected towards their
right in the Northern Hemisphere and blow as the South-West
Monsoon Winds or the Summer Monsoons.
The direc on of the Southwest monsoon winds is mostly controlled
by the physical features of our country.
The Southwest monsoon winds split into two branches when they
reach the southern p of India due to the shape of the Indian
peninsula- The Arabian Sea Branch and The Bay of Bengal Branch.
Tamil Nadu course remains dry during this as it falls in the rain
shadow area of the Arabian Sea branch and is parallel to the Bay of
Bengal branch
Difference between The Arabian Sea Branch and the Bay of Bengal Branch.
ARABIAN SEA BRANCH BAY OF BENGAL BRANCH
Blows from South-West to North-East. Blows from South-East to North-West.
It has higher moisture content. It has compara vely lower moisture
content.
It causes heavy rainfall on the Western It causes moderate rainfall over the
Ghats. Gange c plains and northeast India.
It is crucial for Western India’s agriculture It is important for eastern India’s
especially in the states like Maharashtra agriculture, par cularly in states like West
Gujarat and Karnataka. Bengal Bihar and Odisha.
It contributes significantly to Indias It contributes to the economy through
economy through agriculture and agriculture and inland water transport.
hydroelectric power.
The Season of Retrea ng Monsoon
Dura on and characteris cs
Starts from the middle of September and con nues up to the middle of November.
The process of retreat is low and gradual.
The months of October and November are marked by clear skies and a slight rise in
the temperature.
October heat- This refers to the hot and humid weather condi on experienced in
India during the month of October following the withdrawal of SW Monsoon. A er
the rains recede temperature remains high par cularly in central and southern
India o en exceeding 35 ° C this leads to increase in high humidity level especially
in the tropical and coastal areas. This combina on of heat and humidity makes the
weather uncomfortable as the humidity makes the temperature feel warmer.
Winds begin to blow from land to sea which are generally dry and cool causing a
drop in temperature. With the decrease in rainfall, sky becomes clearer, leading to
sunny days specially in the northern and central parts of India.
During the day, temperature remains high, while night starts ge ng cooler marking
a transi on towards winter.
The retreat of monsoon begins from the Punjab plains in the month of September.
It withdraws from the country by the end of November. At this me, the northeast
trade winds take over and are called the northeast monsoon winds.
The Bay of Bengal is ac ve with Cyclones during this me o en effec ng the
eastern coast of India with heavy rainfall and storms.
