The Northeast Indian Monsoon season is typically defined by the calendar months of October to December (OND), when significant rainfall occurs in the southeastern part of peninsular India. In comparison to the southwest Indian summer monsoon, the northeast monsoon accounts for only about 11% of annual rainfall in India. In the provinces of Tamil Nadu, coastal Andhra Pradesh, and Rayalseema, however, the northeast monsoon contributes anywhere from 30% to 60% of the annual mean. This article will explain to you about the North East Monsoon which will be helpful in preparing Geography for the UPSC Civil services exam.

What are North-East Monsoons?

• The northeast monsoon enters India from the northeast.
• The wind blows from the sea to the land in this type of monsoon.
• The moisture from the Indian Ocean is carried by the monsoon winds.
• The northeast monsoon is limited to south India, bringing rain to Tamil Nadu, Puducherry, Karaikal, Yanam, Andhra Pradesh, Kerala, Mahe, and south interior Karnataka from October to December.
• Low-pressure systems, depressions, and cyclones cause the associated rainfall, also known as the winter monsoon.
• This is Tamil Nadu's main rainy season, with the state receiving 48% (447.4mm) of its annual rainfall during these three months.

The direction of North-East Monsoon in India

The temperature during Northeast Monsoon

• The clouds fade away as the monsoons retreat, and the sky becomes clear.
• The temperature begins to drop significantly during the day.
• Due to a lack of cloud cover, the diurnal temperature range widens.

Pressure and Winds during Northeast Monsoon

• The monsoon trough weakens and shifts southward as the monsoons retreat. As a result, the pressure gradient is minimal.
• The onset of the northeast monsoon is not well defined, unlike the southwest monsoon.
• Local pressure conditions influence the direction of winds in large parts of the country.

Cyclones during Northeast Monsoon

• Tropical cyclones that are the most severe and destructive originate in the Indian Ocean, particularly in the Bay of Bengal.
• The month of October and the first half of November have the highest cyclone frequency.
• More cyclones form in October and November, with the Bay of Bengal producing more cyclones than the Arabian Sea.
• Cyclones in the Bay of Bengal form between 8°N and 14°N in October.
• They move in a west or north westerly direction at first, but many of them eventually recurve and move north-east.
• Nearly half of all Bay storms pass through or affect the Indian coast.
• The coastal belts of Tamil Nadu, Andhra Pradesh, West Bengal, and Odisha are among the areas most vulnerable to these storms.
• Many cyclones that hit India's eastern coast south of 15 degrees north latitude cross the southern peninsula and enter the Arabian Sea.
• They may weaken during this time, but when they re-enter the atmosphere over the Arabian Sea, they intensify into cyclonic storms.
• In October, storms in the Arabian Sea originate between 12°N and 17°N latitudes, and in November, between 8° N and 13° N latitudes.
• They move away from the coast in a north-westerly direction most of the time.
• However, about 25% of them recurve northeast and hit the Maharashtra or Gujarat coast later.

Rainfall during Northeast Monsoon

• With the southwest monsoons retreating, the humidity and cloud cover has decreased significantly, and most parts of the country remain dry.
• The main rainy season in Tamil Nadu and adjoining areas of Andhra Pradesh to the south of the Krishna delta, as well as a secondary rainy season in Kerala, is from October to November.
• While passing over the Bay of Bengal, the retreating monsoons absorb moisture, resulting in this rainfall.

Reasons for Deficient Rainfall during Northeast Monsoon when compared to Southwest Monsoon

• Conditions associated with La Nia increase rainfall associated with the Southwest monsoon, but decrease rainfall associated with the Northeast monsoon.
• The ITCZ's position has also contributed to the current monsoon season's low rainfall.
• The ITCZ’s location during the Northeast Monsoon is to the north of its normal position.

The Northern States during Northeast Monsoons

• In November and December, rain falls in many other parts of the country, including the Gangetic plains and northern states, but this is not due to the northeast monsoon.
• The Western Disturbances, an eastward-moving rain-bearing wind system that originates beyond Afghanistan and Iran and picks up moisture from as far as the Mediterranean Sea and even the Atlantic Ocean, are primarily to blame.
• The precipitation in the higher reaches of Jammu and Kashmir, Himachal Pradesh, and Uttarakhand is frequently in the form of snow.

Conclusion

The northeast monsoon aids in the intensification of rain bands associated with tropical cyclones, increasing the likelihood of daily rainfall significantly. Agricultural production and many other sectors, such as water resources, are affected by the variability of the northeast monsoon rainfall in south peninsular India. Seasonal rainfall from the northeast monsoon has an impact on rice and maize productivity in Tamil Nadu and Andhra Pradesh. There has been a significant decrease in agricultural production across the region during years when the monsoon is deficient

FAQs

MCQs

1. Which of the following regions receives the maximum rainfall from the North-East Monsoon?

A. Western Ghats
B. Coromandel Coast
C. Deccan Plateau
D. Gangetic Plains

2. What is the primary mechanism driving the North-East Monsoon?

A. Westerly winds
B. Retreat of the South-West Monsoon
C. High-pressure system over the Indian subcontinent
D. Formation of cyclones

3. Which state receives more than 50% of its annual rainfall from the North-East Monsoon?

A. Kerala
B. Karnataka
C. Tamil Nadu
D. Maharashtra

4. Which season corresponds to the North-East Monsoon?

A. Summer
B. Winter
C. Spring
D. Autumn

5. Which body of water plays a crucial role in providing moisture to the North-East Monsoon winds?

A. Arabian Sea
B. Indian Ocean
C. Bay of Bengal
D. Mediterranean Sea

GS Mains Questions and Model Answers

Q1: Discuss the importance of the North-East Monsoon for the agricultural economy of Tamil Nadu.

Answer: The North-East Monsoon is vital for Tamil Nadu’s agricultural economy, as the state receives over 50% of its annual rainfall during this period. The rainfall supports the cultivation of paddy, millets, groundnut, and other winter crops. Since Tamil Nadu does not receive significant rainfall during the South-West Monsoon, the North-East Monsoon is crucial for irrigation and ensuring a stable crop yield, particularly in the delta regions where paddy farming is predominant. A failure of the North-East Monsoon can lead to droughts and negatively impact agricultural productivity.

Q2: Analyze the factors responsible for the variability of the North-East Monsoon rainfall.

Answer: The variability of the North-East Monsoon is influenced by several factors, including the movement of the Intertropical Convergence Zone (ITCZ), the formation of cyclones in the Bay of Bengal, and the development of high-pressure systems over northern India. Climate patterns such as El Niño and La Niña also impact the strength and distribution of the North-East Monsoon. For example, El Niño years tend to reduce rainfall, while La Niña years may lead to increased precipitation. Other factors, such as global warming and deforestation, can also contribute to the variability of monsoon rainfall in South India.

Q3: Compare and contrast the South-West Monsoon and the North-East Monsoon in terms of their mechanisms, regions affected, and impact on India’s economy.

Answer: The South-West Monsoon occurs during the summer and is driven by the differential heating of the Indian subcontinent and the Indian Ocean, affecting most parts of India. It brings heavy rainfall to regions like the Western Ghats, Northeast India, and the Gangetic Plains, supporting kharif crops such as rice, cotton, and sugarcane. In contrast, the North-East Monsoon occurs during winter, mainly affecting the southeastern coastal regions like Tamil Nadu. Its mechanism involves the movement of cool, dry winds from the north-east, which pick up moisture from the Bay of Bengal and bring rain to limited regions. While the South-West Monsoon has a larger impact on India's agriculture and economy, the North-East Monsoon is crucial for winter cropping in southern India.

Previous Year Questions from North East Monsoon

1. UPSC CSE Prelims 2017

Question: Which of the following states receives the most rainfall from the North-East Monsoon?
A. Kerala
B. Maharashtra
C. Tamil Nadu
D. West Bengal

Answer: C

Explanation: Tamil Nadu receives the most rainfall from the North-East Monsoon, which occurs between October and December.

2. UPSC CSE Mains 2019 (GS Paper 1)

Question: Explain the mechanism of the North-East Monsoon and its significance for South India’s agriculture.

Explanation: The North-East Monsoon is driven by the high-pressure system that forms over northern India during winter. The cool, dry winds blowing from the north-east pick up moisture from the Bay of Bengal and bring rainfall to the southeastern coastal regions of India. The monsoon is particularly important for South Indian states like Tamil Nadu, where it supports the cultivation of winter crops. Without the North-East Monsoon, regions dependent on this rainfall could face droughts and agricultural losses.