Weather, on the other hand, refers to the current state of the atmosphere at a particular place

and time, including conditions like temperature, humidity, wind speed, and precipitation
occurring right now or in the short term.

The year is divided into seasons based on the monthly variations in these atmospheric
conditions:

● Winter: Characterized by cold temperatures and shorter days.

● Summer: Known for warm to hot temperatures and longer days.
● Rainy Season: Occurs when there is a significant increase in precipitation, often
associated with monsoons or other weather patterns.

Climatic Controls

Climatic conditions are influenced by several key factors:

1. Latitude: The amount of solar energy received varies with latitude due to the curvature
of the Earth. As a result, temperatures generally decrease from the equator towards the
poles.
2. Altitude: Temperature decreases as altitude increases because the atmosphere
becomes less dense at higher altitudes. This explains why hill stations are cooler during
summer compared to lowlands.
3. Pressure and Wind Systems: The pressure and wind systems in an area are
determined by its latitude and altitude. These systems influence temperature and
patterns of rainfall.
4. Distance from the Sea: Proximity to the sea moderates climate variations. Areas farther
inland experience more extreme weather conditions due to continentality, where
summers are hotter and winters colder.
5. Ocean Currents: Coastal climates are influenced by ocean currents. Warm or cold
currents affect coastal temperatures, especially when coupled with onshore winds.
6. Relief Features: Topography significantly affects local climates. Mountains can block
cold or hot winds and influence precipitation patterns by forcing air to rise and cool,
causing rainfall or snowfall.

Factors Affecting India’s Climate

Factors influencing India's climate include:

1. Latitude: India spans across various latitudes influenced by the Tropic of Cancer,
resulting in a mix of tropical and subtropical climates.
2. Altitude: With mountains in the north and low coastal areas, India's elevation varies
significantly. The northern mountains moderate winter temperatures compared to the
plains.
 3. Pressure and Winds: India's climate is shaped by:
○ Surface Winds: Monsoon winds originating from the southern Indian Ocean
bring moisture-laden air towards the subcontinent, causing seasonal rainfall.
○ Upper Air Circulation: Jet streams, fast-flowing currents in the upper
atmosphere, impact weather patterns.
4. Western Cyclonic Disturbances and Tropical Cyclones: These weather systems
bring significant rainfall and influence regional weather patterns.

The Indian Monsoon

The Indian Monsoon is a crucial weather phenomenon that significantly influences India's
climate:

1. Seasonal Reversal of Winds: Monsoon refers to the seasonal reversal of wind

direction. During summer, landmasses in India heat up more than surrounding oceans,
creating low-pressure areas over land and high-pressure areas over the seas.
2. Inter-Tropical Convergence Zone (ITCZ): The shift of the ITCZ over the Ganga plain
during summer, known as the monsoon trough, brings heavy rainfall to the region.
3. High-Pressure Systems: A high-pressure area east of Madagascar and over the Indian
Ocean affects the monsoon by influencing wind patterns.
4. Tibetan Plateau: Intense heating of the Tibetan Plateau creates low-pressure systems
at high altitudes, contributing to the monsoon's strength.
5. Jet Streams: The movement of the westerly jet stream north of the Himalayas and the
tropical easterly jet stream over the Indian peninsula during summer also play significant
roles in the monsoon's behavior.
6. Southern Oscillation (SO): Variations in pressure conditions over the southern oceans,
coupled with irregular wind and sea surface temperature changes in the tropical eastern
Pacific Ocean (known as Southern Oscillation), affect monsoon patterns in the tropics
and subtropics.

The Onset of the Monsoon and Withdrawal

The onset and progression of the monsoon in India follow a distinct pattern each year:

Duration and Timing: The monsoon typically lasts for about 100-120 days, starting from early
June to mid-September. The arrival of the monsoon is marked by a sudden increase in rainfall,
known as the "burst" of the monsoon.

Arrival in Different Regions:

● Southern India: The monsoon first reaches the southern tip of the Indian peninsula by
the first week of June.
● Branches: It then splits into two branches - the Arabian Sea branch and the Bay of
Bengal branch.
● Mumbai: The Arabian Sea branch reaches Mumbai around June 10th.
 ● Assam: The Bay of Bengal branch reaches Assam by the first week of June.
● Central India: By mid-June, the Arabian Sea branch extends over Saurashtra-Kuchchh
and central India.
● Northwestern Plains: Both branches merge over the northwestern part of the Ganga
plains.
● Delhi: Delhi receives monsoon showers from the Bay of Bengal branch by the end of
June.
● Northern India: By the first week of July, western Uttar Pradesh, Punjab, Haryana, and
eastern Rajasthan experience monsoon rains.
● Complete Coverage: By mid-July, the monsoon covers Himachal Pradesh and spreads
across the rest of the country.

Withdrawal of the Monsoon

The withdrawal of the monsoon from India follows a gradual pattern:

1. Start of Withdrawal: The monsoon begins to withdraw from the northwestern states of
India by early September.
2. Northern Peninsula: By mid-October, the monsoon withdraws completely from the
northern half of the peninsula.
3. Southward Progression: The withdrawal progresses southward:
○ North to South: From north to south, the withdrawal occurs between the first
week of December to the first week of January.
○ Completion: By early December, the monsoon has withdrawn from the rest of
the country.

The Seasons of India

India experiences four distinct seasons throughout the year, each characterized by unique
weather patterns and agricultural significance:

1. The Cold Weather Season (Winter):

● Duration: Mid-November to February.

● Features: December and January are the coldest months, with temperatures decreasing
from south to north. Days are warm with cold nights, clear skies, low humidity, and
variable winds.
● Significance: Critical for cultivating 'rabi' crops.

2. The Hot Weather Season (Summer):

● Duration: March to May.

● Features: Rising temperatures and falling air pressure, especially in northern India.
'Loo', strong hot dry winds, are common. Pre-monsoon showers aid in mango ripening.
 ● Significance: Preparation for the monsoon; early mango crop ripening due to
pre-monsoon showers.

3. Advancing Monsoon (Rainy Season):

● Duration: June to September.

● Mechanism: Southwest monsoon winds originating from the southeast cross the
equator and enter India, covering the country over a month.
● Features: Mawsynram receives the highest average rainfall globally. Monsoon
characterized by breaks and tropical depressions affecting rainfall intensity.
● Significance: Vital for agriculture; planting and growth of 'kharif' crops depend on
monsoon rains.

4. Retreating Monsoon (Transition Season):

● Duration: October to November.

● Features: Clear skies and rising temperatures mark the retreat of monsoon. Days are
hot, nights are cool and pleasant initially but become oppressive due to high humidity
('October heat').
● Significance: Transition from rainy season to dry winter conditions; critical for harvesting
'kharif' crops and preparing for winter crops.

These seasons play a crucial role in shaping India's agriculture, economy, and daily life, each
bringing its own set of challenges and opportunities.

Distribution of Rainfall in India

India exhibits a diverse pattern of rainfall distribution across its vast geography, influencing its
agricultural and ecological diversity:

1. High-Rainfall Regions:

● Western Coast and Northeastern India: Receive over 400 cm of rainfall annually.
● Features: Lush vegetation and tropical climate supported by heavy monsoon rains.

2. Low-Rainfall Regions:

● Western Rajasthan, Gujarat, Haryana, Punjab: Receive less than 60 cm of rainfall

annually.
● Features: Arid and semi-arid landscapes, characterized by desert and dry scrub
vegetation.

3. Moderate-Rainfall Regions:

● Interior Deccan Plateau and East of Sahyadris: Experience moderate rainfall.

● Features: Mixed vegetation, including deciduous forests and grasslands.