FACTORS BEHIND THE HEAVY RAIN (Syllabus: GS Paper 1 – Geography)

Context: Recently, at least 80% of India received rainfall, with heavy to very heavy spells lashing Assam, West Bengal, Uttar Pradesh, Uttarakhand, Gujarat, Maharashtra's coast, Karnataka, Kerala, and Lakshadweep.

Monsoon Climate of India

• About: India's climate is characterized as 'monsoon' type, predominantly found in South and Southeast Asia.
• Seasonal Divisions: India's climate has four seasonal divisions, with two dedicated to the monsoon period.
• Southwest Monsoon Season: The southwest monsoon brings seasonal rainfall from June to September.
• Retreating Monsoon Season: The retreating monsoons occur during October and November.

Factors Behind the Heavy Rain

• Westerly Winds: Continuous influx of moisture-laden westerly winds from the Arabian Sea has significantly contributed to the enhanced rainfall.
• Monsoon Trough Position: The monsoon trough's southward shift has increased rainfall in central, eastern, and peninsular India.
• Northward Trough Shift: When the monsoon trough shifts northward, the Himalayan foothills receive more rainfall, while the rest of India experiences less.
• Additional Weather Systems: Other weather systems have also played a role in the widespread rainfall, excluding extreme northern India.

oThe persistence of an off-shore trough (a shallow trough of low pressure, which develops along India’s coast during the monsoon) between south Gujarat and north Kerala for more than a week now.

oThe intermittent development of a wind shear zone where winds move with different velocities and directions along latitudes 20 ° N between central and peninsular India.