Syllabus:

GS-1: Salient features of the World’s Physical Geography; Important Geophysical phenomena

Context: The India Meteorological Department (IMD) announced that the southwest monsoon has arrived over parts of the Bay of Bengal and Andaman Sea at least a week before its scheduled arrival time. 

More on the News

• This year marks the region's earliest monsoon onset in seven years, preceding IMD's normal date of May 21 for the South Andaman Sea and Port Blair.

Monsoon in India

• Monsoon refers to the seasonal reversal in the direction of winds and the associated rainfall. This word is derived from the Arabic word “Mausim”.
• Southwest Monsoon:
  It occurs from June to September. It hits Kerala on the southwestern coast and then proceeds across the country.
  This is the main monsoon impacting India, bringing relief from the heat and significantly supporting the ecosystem, economy, and kharif crop cultivation.
  Over 70 percent of India’s annual rainfall occurs between June and September, with a Long Period Average of 880 mm.
• Northeast Monsoon:
  It occurs from October to December and affects peninsular India. It is not as intense as the southwest monsoon but is crucial for the growth of rabi crops.
  It is crucial for Tamil Nadu, Kerala, Puducherry, Karaikal, coastal Andhra Pradesh, Rayalaseema, and Yanam. Tamil Nadu gets about 48% (443.3 mm) of its annual rainfall from October to December, which is vital for rabi crops.
  It is also known as the winter monsoon, retreating monsoon, or reverse monsoon.

Effects of climate change on Changing Rain Pattern in India due to Climate Change

• Traditionally drier regions like Rajasthan, Gujarat, Konkan, central Maharashtra, and parts of Tamil Nadu saw over a 30% rise in southwest monsoon rainfall compared to the 1981–2011 average.
• Traditionally high rainfall regions like Assam and Meghalaya experienced a decline in monsoon precipitation.
• Southwest monsoon rainfall increased in 55% of India’s tehsils, driven mainly by short, intense downpours that often lead to flash floods.
• During the southwest monsoon in India, wet extremes account for an increasing share of total seasonal rainfall.
• The retreating monsoon rainfall spiked by more than 10% in approximately 80% of tehsils in Tamil Nadu, 44% in Telangana, and 39% in Andhra Pradesh.