Relevance for UPSC: GS Paper I (Geography – Climate & Weather Systems) and GS Paper III (Disaster Management, Environment) 

Tropical cyclones are among nature’s most powerful weather systems — swirling masses of wind and rain that form over warm ocean waters. In October 2025, two major storms — Cyclone Montha over the Bay of Bengal and Hurricane Melissa over the Atlantic Ocean — reminded the world of the immense energy locked within our oceans. Understanding how such storms form, behave, and are measured is essential for preparedness and disaster mitigation.

How Cyclones Form

The formation of a cyclone, known as cyclogenesis, depends on a combination of atmospheric and oceanic conditions:

1. Warm Ocean Waters: Sea surface temperatures of at least 26.5°C provide the heat and moisture that fuel cyclones. The warm air rises, creating a low-pressure zone near the ocean surface.
   
2. High Humidity and Converging Winds: Moist air from the surrounding regions flows into the low-pressure zone. As it rises and cools, the moisture condenses into clouds, releasing latent heat, which further drives the system.
   
3. Coriolis Effect: The Earth’s rotation causes the air to spin, giving the cyclone its characteristic rotation — anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
   
4. Low Vertical Wind Shear: When there’s little difference in wind speed between the surface and upper atmosphere, the storm can organise and intensify.
   
5. Sustained Energy Source:As long as the cyclone remains over warm waters, it continues to strengthen. When it moves over land or cooler waters, it begins to lose energy.
   

Cyclone Montha: Over the Bay of Bengal

• Formation: Cyclone Montha developed over the southeastern Bay of Bengal in late October 2025.
  
• Path: It moved northwestward, approaching the coasts of Andhra Pradesh and Odisha, bringing heavy rainfall and gusty winds before weakening into a deep depression.
  
• Wind Speed: Peak winds were estimated around 85–90 km/h, classifying it as a Cyclonic Storm under the India Meteorological Department (IMD) scale.
  
• Impact: Montha caused coastal flooding, uprooted trees, and disrupted power supply in coastal districts, though early warnings helped minimise casualties.
  
• Scientific Significance: It formed in an active post-monsoon phase, when the Bay of Bengal remains warm and favourable for cyclogenesis. It also highlighted how small systems can intensify quickly under warming seas.
  

Hurricane Melissa: Over the Atlantic

• Formation: Melissa formed in mid-October 2025 over the central Atlantic Ocean, evolving from a tropical depression into a Category 3 hurricane on the Saffir-Simpson scale.
  
• Characteristics: With wind speeds exceeding 180 km/h and a central pressure around 960 mb, Melissa was a classic example of a well-structured, high-intensity hurricane.
  
• Track: It moved northwest toward Bermuda, causing storm surges and torrential rain before curving away into the North Atlantic.
  
• Insight: Melissa’s rapid intensification — strengthening from a tropical storm to a major hurricane in under 48 hours — underscored the growing role of climate change and ocean heat anomalies in powering extreme weather.
  

How Cyclones Are Measured

Cyclones are monitored using a combination of satellite data, ocean buoys, weather radars, and numerical models.

1. Parameters Used

• Wind Speed: Primary indicator of intensity; measured using anemometers or estimated via satellite imaging.
  
• Central Pressure: Lower pressure indicates stronger cyclones — intense storms can drop below 950 millibars.
  
• Storm Surge Height: Represents sea-level rise due to the storm’s winds and pressure; a key cause of coastal damage.
  
• Rainfall Intensity and Spread: Assessed using Doppler radar and satellites to forecast flooding potential.
  

2. Intensity Classification

• India Meteorological Department (IMD) Scale
  
  • Cyclonic Storm: 62–88 km/h
    
  • Severe Cyclonic Storm: 89–117 km/h
    
  • Very Severe Cyclonic Storm: 118–166 km/h
    
  • Super Cyclonic Storm: 222 km/h and above
    
• Saffir-Simpson Scale (used for hurricanes):
  
  • Category 1 to 5 based on wind speeds from 119 km/h (Category 1) to 252 km/h (Category 5).
    

3. Tools and Technology

• Satellites (INSAT, NOAA, METEOSAT): Provide real-time imagery and data on cloud structure and wind speed.
  
• Doppler Weather Radars (DWRs): Track rainfall intensity and storm movement along Indian coasts.
  
• Automatic Weather Stations and Buoys: Record ocean temperature, humidity, and wind conditions.
  
• Numerical Weather Prediction Models: Simulate storm behaviour and help forecast landfall location and timing.
  

Why Monitoring Matters

For India, where nearly 7,500 km of coastline faces frequent cyclones, accurate monitoring saves lives and livelihoods. Initiatives like the National Cyclone Risk Mitigation Project (NCRMP) and IMD’s early warning systems have significantly reduced fatalities compared to previous decades.

The increasing frequency of intense storms like Montha and Melissa also raises concern over climate-induced ocean warming, which is fuelling stronger and faster-developing systems.

Important Terms

1. Cyclogenesis: The process by which a tropical disturbance develops into a cyclone.
   
2. Coriolis Effect: The deflection of moving air due to Earth’s rotation, giving cyclones their spin.
   
3. Storm Surge: An abnormal rise of seawater during a cyclone, often leading to flooding.
   
4. Vertical Wind Shear: The difference in wind speed/direction with height; high shear disrupts cyclone formation.
   
5. Central Pressure: The atmospheric pressure at the cyclone’s core — lower values mean stronger storms.
   
6. Rapid Intensification: A sharp increase in wind speed (≥55 km/h within 24 hours), often linked to ocean heat content.
   

Key Takeaways

• Cyclones form over warm tropical seas due to rising moist air, low pressure, and Earth’s rotation.
  
• Cyclone Montha and Hurricane Melissa (2025) illustrate how tropical storms differ across oceans but share similar mechanics.
  
• Measurement involves wind speed, pressure, rainfall, and storm surge — monitored by satellites and radar systems.
  
• India’s disaster preparedness and IMD’s warning systems have improved, yet rising ocean temperatures pose a growing threat.
  

UPSC Mains Question:
Explain the process of tropical cyclone formation. Compare the monitoring and classification mechanisms used by India Meteorological Department and global agencies such as NOAA.

One-Line Wrap:
From Cyclone Montha to Hurricane Melissa — understanding how storms form and are measured is the first step toward surviving nature’s most powerful winds.