Mains Practice Questions

Introduction

The Indian subcontinent, with an 8,041 km coastline, is highly vulnerable to cyclones, with the Bay of Bengal witnessing nearly 4 times the number of cyclones as the Arabian Sea.

• This phenomenon is influenced by geographical, meteorological, and oceanic factors, exacerbated by climate change and anthropogenic activities.

Body

Reasons for Higher Cyclonic Activity in the Bay of Bengal than Arabian Sea:

• Geographical and Oceanographic Factors:
  • Funnel-like Shape: The Bay’s concave structure directs and amplifies storm surges toward the coasts of India, Bangladesh, and Myanmar, intensifying their impacts.
    • This unique geography is absent or minimal in the Arabian Sea, which lacks a similarly pronounced funnel-like shape, reducing the amplification of storm surges.
  • Shallow Coastal Waters: These waters allow storm surges to rise significantly higher, causing severe flooding when cyclones make landfall.
• Favorable Climatic and Meteorological Conditions
  • High Sea Surface Temperatures (SSTs): SSTs in the Bay of Bengal remain consistently above 28°C, often exceeding 30°C–32°C, which is ideal for cyclone formation.
    • Warm SSTs fuel moisture-laden air and evaporation, providing energy for storms to intensify.
  • Warm Water Influx from Rivers: Major rivers like the Ganga, Brahmaputra, and Irrawaddy discharge warm freshwater into the Bay, preventing the cooling of surface waters.
    • Unlike the Arabian Sea, where water mixes vertically, the Bay’s stratified layers sustain warm surface temperatures.
• Atmospheric Dynamics
  • Weak Wind Shear:In the Bay, the vertical difference in wind speeds (wind shear) is relatively low, allowing cyclones to develop and maintain structure.
  • Moisture-Laden Winds: Warm, humid air currents over the Bay enhance cyclone intensity, particularly during pre-monsoon and post-monsoon seasons.
• Other Factors:
  • Post-Monsoon Effect: The retreating monsoon during October-November creates favorable conditions for cyclones in the Bay, with low-pressure zones and stagnant winds aiding their genesis.

Recent Key Cyclones Hitting India’s East Coast:

• Cyclone Amphan (2020):
  • Intensity: Super Cyclonic Storm.
  • Impact: Massive destruction to eastern India especially West Bengal & Odisha
• Cyclone Yaas (2021):
  • Intensity: Very Severe Cyclonic Storm.
  • Impact: Severe flooding in Odisha and West Bengal.
• Cyclone Mocha (2023):
  • Intensity: Extremely Severe Cyclonic Storm.
  • Impact: Widespread destruction in Bangladesh and Myanmar.

Conclusion

Bay of Bengal's geographical features and high sea surface temperatures make it more prone to cyclones, with climate change intensifying their frequency and severity. Although the Arabian Sea was traditionally less active, recent cyclones like Tauktae(2021) and Biparjoy (2023) highlight the growing threat attributed to warming seas.