Rainfall Dynamics: Chennai vs. Mangalore and the Arctic Connection
Q: Chennai and Mangalore approximately lie on the same latitude, yet both places receive different amount of rainfall in different months. Why? How do you foresee the role of Arctic Sea in India's monsoon system? Discuss.
Despite being on a similar latitude, Mangalore and Chennai exhibit starkly different rainfall regimes. This is primarily due to their geographic location relative to the moisture-laden winds and mountain barriers.
1. Why Rainfall Differs Between Chennai and Mangalore
- Seasonal Timing: Mangalore receives heavy rain (June–Sept) from the Southwest Monsoon (Arabian Sea branch). Chennai receives its maximum rain (Oct–Dec) from the Northeast Monsoon (Retreating Monsoon).
- Orographic Effect: Mangalore lies on the windward side of the Western Ghats, causing air to rise and condense (Orographic rain). Chennai lies in the rain shadow region during the SW monsoon.
- Coastal Orientation: During the SW monsoon, winds blow parallel to the Coromandel Coast (Chennai), yielding little rain. In contrast, the NE monsoon picks up moisture from the Bay of Bengal before hitting Chennai.
2. Role of the Arctic Sea in the Monsoon System
Recent climatic studies highlight a Teleconnection between Arctic warming and the Indian monsoon.
- Atmospheric Waves: Melting Arctic ice alters Rossby Waves and shifts the Jet Streams. According to 2026 research, Arctic amplification (faster warming at poles) weakens the temperature gradient between the poles and tropics.
- Impact: This leads to increased variability. Reduced Arctic sea ice often correlates with extreme rainfall events in Central India but may cause monsoon deficits in Peninsular regions.
Definition of Key Term
Orographic Rainfall: Rain produced when moisture-laden air is forced to rise over a mountain range. Example: Mangalore receives over 3000mm of rain as the Western Ghats trap the Arabian Sea winds.
Conclusion
The contrast between Chennai and Mangalore proves that topography is as vital as latitude. Furthermore, the Arctic-Monsoon link underscores that the Indian monsoon is now a global atmospheric phenomenon, requiring climate-resilient planning to mitigate the risks of erratic weather.
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