GS-1:Salient Features of World Physical Geography; Important Geophysical phenomena (earthquakes, tsunami, volcanoes, cyclones); Geographical features and location;

In News:Monsoon 2024 ends with 8% more rain than historical average: IMD

2.Discuss the factors influencing the southwest monsoon rainfall in India.

The southwest monsoon is a crucial climatic phenomenon that significantly impacts the Indian subcontinent. It typically occurs between June and September, bringing substantial rainfall essential for agriculture and water resources.

Factors influencing the southwest monsoon rainfall in India:

1. Differential heating of land and water: The landmass of India heats up more quickly than the surrounding seas during summer, creating a low-pressure area over the land. This pressure difference draws in moisture-laden winds from the Indian Ocean, initiating the monsoon.
2. Inter-Tropical Convergence Zone (ITCZ):The ITCZ is a low pressure belt around the equator that shifts northward during summer. Its movement over India brings moisture-laden winds from the Indian Ocean, leading to rainfall.

3. Presence of water bodies: The Arabian Sea, Bay of Bengal, and Indian Ocean provide significant moisture to the southwest monsoon winds. These water bodies are essential for the accumulation of moisture that leads to precipitation.
4. Geographical relief: The Himalayas and Western Ghats play crucial roles in influencing monsoon rainfall in India. The Himalayas force the monsoon winds southwards, while the Western Ghats cause orographic rainfall.
5. High-pressure systems: The presence of high-pressure areas, such as that east of Madagascar, influences wind patterns and can affect the strength and direction of the monsoon winds.
6. Jet streams: The position and movement of jet streams, particularly the westerly jet stream during summer, can impact monsoon dynamics by influencing weather patterns over the Indian subcontinent.
7. Global climate phenomena:

● Events like El Niño and La Niña in the Pacific Ocean can significantly affect monsoon behaviour. For instance, El Niño is often associated with weaker monsoons and below-normal rainfall.

● Indian Ocean Dipole (IOD) involves fluctuations in sea surface temperatures between the western and eastern Indian Ocean. A positive IOD can enhance monsoon rainfall, while a negative IOD can suppress it.

● Arctic Oscillation (AO) can influence the jet stream, which in turn affects the monsoon’s path and intensity. A negative AO can favour above-normal monsoon rainfall.

8. Local factors: Regional topography and local climatic conditions can lead to variations in rainfall distribution across different parts of India. Areas in rain shadow regions receive significantly less rainfall compared to windward areas.

These factors collectively influence not only the quantity but also the timing and spatial distribution of southwest monsoon rainfall, which is vital for agriculture and water resources in India.

PYQ

1. Why is the South-West Monsoon called Purvaiya’ (easterly) in Bhojpur Region? How has this directional seasonal wind system influenced the cultural ethos of the region? 2023
2. How far do you agree that the behavior of the Indian monsoon has been changing due to humanizing landscapes? Discuss.2015
3. What characteristics can be assigned to monsoon climate that succeeds in feeding more than 50 percent of the won population residing in Monsoon Asia?2017

Source:https://www.thehindu.com/news/national/above-normal-rain-likely-in-central-southern-peninsular-northeast-india-from-october-to-december-says-imd/article68705674.ece