Cyclones
Cyclone Montha makes landfall in AP
Why in the News?
Cyclone Montha, classified as a severe cyclonic storm, has made landfall near Kakinada (Andhra Pradesh) on October 28.
Back2Basics: Tropical Cyclones
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What is the Landfall of a Cyclone?
- Overview: A tropical cyclone is said to make landfall when its centre (eye) crosses the coastline from sea to land.
- Not the Same as a Direct Hit:
- Landfall = when the eye crosses the coast.
- Direct hit = when the eyewall (zone of strongest winds) impacts the coast, even if the centre remains offshore.
- Duration: Landfall usually lasts a few hours, depending on wind speed and storm size.
- Post-Landfall Behaviour: Cyclones lose intensity rapidly after landfall due to loss of oceanic moisture and increased land friction.
Behind the Naming of Cyclones:
- Overview: Cyclones in the North Indian Ocean are named under the World Meteorological Organization (WMO) / United Nations Economic and Social Commission for Asia and the Pacific (ESCAP) Panel on Tropical Cyclones (since 2004).
- Naming Authority: Regional Specialized Meteorological Centre (RSMC), New Delhi, operated by IMD.
- 13 Member Countries: Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, Thailand, Yemen, Iran, Qatar, Saudi Arabia, and UAE.
- Submission of names: Each country submits 13 culturally neutral, gender-neutral names, forming a 169-name rotating list.
- Non-repetition: Names are used sequentially and not repeated after one use.
- “Montha”: It was suggested by Thailand, meaning “beautiful” or “fragrant flower.”
- Significance: Naming helps public communication, ensures clarity in warnings, and avoids confusion during multiple simultaneous storms.
- Current sequence: Shakthi (Sri Lanka) → Montha (Thailand) → Senyar (UAE) → Ditwah (Yemen) → Arnab (Bangladesh) → Murasu (India).
| [UPSC 2020] Consider the following statements:
1. Jet streams occur in the Northern Hemisphere only. 2. Only some cyclones develop an eye. 3. The temperature inside the eye of a cyclone is nearly 10°C lesser than that of the surroundings. Which of the statements given above is/are correct? (a) 1 only (b) 2 and 3 only (c) 2 only* (d) 1 and 3 only |
Cyclones
Cyclone Shakhti forms over Arabian Sea
Why in the News?
The India Meteorological Department (IMD) confirmed the formation of Cyclone Shakthi (named by Sri Lanka) over the northeast Arabian Sea.
About Cyclogenesis in the Arabian Sea:
- Overview: Cyclogenesis is the formation and intensification of tropical cyclones under favourable oceanic and atmospheric conditions.
- Seasonality: Most active during pre-monsoon (Apr–Jun) and post-monsoon (Oct–Dec) periods, when sea surface temperatures (SSTs) exceed 27 °C, moist convection intensifies, and the Coriolis effect induces rotation.
- Formation Process: Warm moist air rises forming low pressure; latent heat of condensation deepens the system; upper-level outflow and low vertical wind shear sustain vertical growth, producing a warm eye with spiral rainbands.
- Historical Pattern: The Arabian Sea was once less cyclone-prone than the Bay of Bengal due to cooler waters, dry winds, and high wind shear. Limited basin size and monsoon winds restricted cyclone growth.
- Recent Change: Ocean warming and climate change have sharply increased cyclonic activity, making the region far more active in the last decade.
- Rapid Intensification Trend: Short-term surges in wind speed (< 24 hrs) are now common, linked to warmer SSTs, Indian Ocean Dipole (IOD) shifts, and monsoon wind variability.
- Oceanic–Climatic Drivers:
- Indonesian Throughflow imports warm Pacific waters, raising SSTs.
- Southern Ocean inflow brings cooler deep water, stabilising lower layers.
- Dual cyclone seasons arise from monsoon wind reversal unique to the region.
- Climate Change Impact:
- IMD data show a 52 % rise in Arabian Sea cyclones in two decades, while Bay of Bengal activity slightly declined.
- The Indian Ocean is among the fastest-warming oceans, increasing heat-moisture availability, altering global weather, and heightening coastal risks to life and infrastructure.
Recent Examples:
- Tauktae (2021) – winds > 185 km/h, heavy damage along Gujarat–Konkan.
- Biparjoy (2023) – lasted 13 days, fed by SSTs ~31 °C.
- Tej (2023) – hit Oman & Yemen, showing cross-basin movement.
- Shakthi (2025) – latest late-season, fast-intensifying cyclone.
Back2Basics: Tropical Cyclones
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| [UPSC 2020] Consider the following statements:
1. Jet streams occur in the Northern Hemisphere only. 2. Only some cyclones develop an eye. 3. The temperature inside the eye of a cyclone is nearly 10°C lesser than that of the surroundings. Which of the statements given above is/are correct? (a) 1 only (b) 2 and 3 only (c) 2 only* (d) 1 and 3 only |
Cyclones
On uncommon cyclones in the Arabian Sea
Note4Students
From UPSC perspective, the following things are important :
Prelims level: Tropical and temperate cyclone;
Mains level: Impact of climate change on cyclone;
Why in the News?
A rare August cyclone, named ‘Asna’, currently positioned off the Kutch coast is even more remarkable for having originated over land.
Why was there a lot of excitement over Asna?
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Why does the North Indian Ocean have two cyclone seasons?
The North Indian Ocean has two distinct cyclone seasons due to the unique monsoonal circulation patterns in the region:
- Pre-monsoon season (March-May): The Arabian Sea warms rapidly during this time as the sun crosses over to the Northern Hemisphere. The Bay of Bengal is relatively warmer and begins producing atmospheric convection and rainfall. This leads to cyclogenesis in both the Arabian Sea and the Bay of Bengal.
- Post-monsoon season (October-December): This is the northeast monsoon season for India. The Arabian Sea cools due to the strong southwesterly winds and mixing of cold subsurface waters. However, the Bay of Bengal remains favourable for cyclogenesis. The post-monsoon season is the major cyclone season in the North Indian Ocean
How is climate change affecting the region?
- Warming of the Indian Ocean: Climate change is amplifying the warming of the Indian Ocean, with more heat being transferred from the Pacific Ocean and Southern Ocean. This increases the overall sea surface temperature (SST), crucial for cyclone formation.
- Monsoon and cyclones: The warming affects the monsoon patterns and has the potential to change cyclone intensity. More heat and moisture from the warming seas lead to more energy available for cyclones.
- Impact on global ocean circulation: The warming of the Indian Ocean is also affecting global ocean currents, impacting heat uptake by the Pacific Ocean and water sinking in the North Atlantic. The Indian Ocean is playing a central role in global climate change processes.
Way forward:Â
- Strengthening Early Warning Systems: Enhance real-time monitoring and forecasting of cyclones, particularly in the pre- and post-monsoon seasons, using satellite data and advanced models.
- Building Climate Resilience: Implement climate adaptation strategies, especially for coastal communities, by improving infrastructure and disaster preparedness to cope with increasing cyclone intensity due to climate change.
Mains PYQ:
Q Discuss the meaning of colour-coded weather warnings for cyclone prone areas given by India Meteorological Department. (UPSC IAS/2022)
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