Cyclones in India
Tropical Cyclones are one of the most devastating natural disasters affecting India's coastal regions. India is particularly vulnerable due to its long coastline and geographical location in the tropical zone.
What are Cyclones?
Definition
Cyclone: Intense low-pressure weather system with rotating winds
Wind Speed: Minimum 62 km/hr for tropical cyclone classification
Structure: Eye (calm center), eye wall (strongest winds), spiral bands
Movement: Counterclockwise in Northern Hemisphere
==== Formation Conditions ####
Sea Surface Temperature: Above 26.5°C
Ocean Depth: At least 60 meters deep warm water
Low Wind Shear: Minimal difference in wind speeds at different altitudes
Coriolis Effect: Sufficient earth's rotation (away from equator)
Atmospheric Instability: Rising air and low pressure
Cyclone Classification
==== Based on Wind Speed (IMD Classification) ####
| Category | Wind Speed (km/hr) | Description |
| Depression | 31-49 | Weak circulation |
| Deep Depression | 50-61 | Organized circulation |
| Cyclonic Storm | 62-88 | Tropical cyclone |
| Severe Cyclonic Storm | 89-117 | Dangerous winds |
| Very Severe Cyclonic Storm | 118-166 | Very dangerous |
| Extremely Severe Cyclonic Storm | 167-221 | Extremely dangerous |
| Super Cyclonic Storm | 222+ | Catastrophic damage |
Cyclone-Prone Areas in India
==== Bay of Bengal ####
Characteristics:
Frequency: 4-5 cyclones annually
Season: April-May, October-December
Intensity: Generally more intense than Arabian Sea cyclones
Path: Moves towards east coast (Odisha, Andhra Pradesh, Tamil Nadu, West Bengal)
Most Affected States:
Odisha - Highest cyclone frequency
Andhra Pradesh - Significant damage from storms
West Bengal - Including Kolkata metropolitan area
Tamil Nadu - Southern coastline affected
==== Arabian Sea ####
Characteristics:
Frequency: 1-2 cyclones annually
Season: May-June, October-November
Intensity: Generally less intense but increasing recently
Path: Affects western coast (Gujarat, Maharashtra, Kerala, Karnataka)
Most Affected States:
Gujarat - Frequent landfall location
Maharashtra - Mumbai region vulnerable
Kerala - Southern tip affected
Karnataka - Coastal areas
Cyclone Seasons
| Season | Period | Characteristics | Major Areas Affected |
| Pre-Monsoon | April-May | Bay of Bengal active | East coast |
| Monsoon | June-September | Suppressed activity | Limited cyclones |
| Post-Monsoon | October-December | Peak season | Both coasts |
| Winter | January-March | Rare occurrence | Minimal activity |
Notable Cyclones in Indian History
==== Devastating Cyclones ####
| Cyclone | Year | Affected Area | Death Toll | Wind Speed |
| Bhola Cyclone | 1970 | East Pakistan (now Bangladesh) | 300,000+ | 185 km/hr |
| 1999 Odisha Cyclone | 1999 | Odisha | 10,000+ | 260 km/hr |
| Cyclone Nargis | 2008 | Myanmar (affected Indian states) | 138,000+ | 215 km/hr |
| Cyclone Phailin | 2013 | Odisha, Andhra Pradesh | 45 | 215 km/hr |
| Cyclone Fani | 2019 | Odisha | 89 | 180 km/hr |
==== Recent Significant Cyclones ####
Cyclone Amphan (2020):
Cyclone Yaas (2021):
Affected areas: Odisha, West Bengal
Category: Very severe cyclonic storm
Evacuation: 12 lakh people
Deaths: 20+
Cyclone Tauktae (2021):
Affected areas: Gujarat, Maharashtra
Category: Extremely severe cyclonic storm
Arabian Sea: Strongest cyclone in decades
Deaths: 174
==== Bay of Bengal ####
Why More Active?
Warmer waters: Higher sea surface temperatures
Monsoon convergence: Favorable atmospheric conditions
Low wind shear: Less disruption to cyclone development
Geographical shape: Funnel shape concentrates storms
Formation Areas:
Central Bay of Bengal: Most cyclones originate here
South Bay of Bengal: Near Sri Lanka and Tamil Nadu
North Bay of Bengal: Affects Bengal and Bangladesh
==== Arabian Sea ####
Recent Changes:
Increasing frequency: Climate change impact
Higher intensity: Warmer sea surface temperatures
Extended season: Cyclones in unusual months
Impact and Damage
==== Physical Impact ####
Wind Damage:
Infrastructure destruction: Buildings, power lines, communication towers
Uprooted trees: Blocking roads and railways
Crop damage: Agricultural losses
Storm Surge:
Coastal flooding: Sea water intrusion inland
Height: Can reach 3-5 meters above normal sea level
Saltwater intrusion: Agricultural land contamination
Rainfall:
Flooding: Heavy precipitation causes inland flooding
Landslides: In hilly areas due to saturated soil
Waterlogging: Urban areas with poor drainage
==== Socio-Economic Impact ####
Loss of life: Direct and indirect casualties
Economic losses: Infrastructure, agriculture, industry
Displacement: Temporary and permanent migration
Livelihood impact: Fishing, agriculture, tourism
Cyclone Preparedness and Management
==== Early Warning System ####
India Meteorological Department (IMD):
Satellite monitoring: Continuous tracking
Numerical models: Prediction and path forecasting
Color-coded warnings: Green, Yellow, Orange, Red
Lead time: 72-hour advance warning
Warning Dissemination:
Media: TV, radio, newspapers
Mobile alerts: SMS warnings
Sirens: Coastal warning systems
Community announcements: Local authorities
==== Disaster Preparedness ####
Government Measures:
National Disaster Management Authority (NDMA)
State Disaster Management Authorities (SDMAs)
District Disaster Management Plans
Evacuation protocols
Infrastructure:
Cyclone shelters: Multi-purpose buildings
Emergency supplies: Food, water, medicines
Communication systems: Emergency networks
Evacuation routes: Pre-planned safe corridors
==== Response and Relief ####
Immediate Response:
Search and rescue operations
Medical emergency services
Restoration of essential services
Relief distribution
Long-term Recovery:
Climate Change and Cyclones
==== Changing Patterns ####
Increased intensity: Stronger cyclones due to warmer oceans
Changed tracks: Unusual paths and landfall locations
Extended seasons: Cyclones in non-traditional months
Rapid intensification: Faster strengthening of storms
==== Future Projections ####
Frequency: May decrease overall but increase in intensity
Sea level rise: Increased storm surge impact
Rainfall: More extreme precipitation events
Economic impact: Exponential increase in damage costs
Mitigation Strategies
==== Structural Measures ####
Coastal embankments: Sea walls and barriers
Storm-resistant buildings: Cyclone-proof construction
Drainage systems: Improved urban flood management
Mangrove restoration: Natural storm buffers
==== Non-structural Measures ####
Early warning systems: Advanced forecasting
Community preparedness: Training and awareness
Land use planning: Restricting development in vulnerable areas
Insurance schemes: Risk transfer mechanisms
UPSC Relevance
Papers: GS Paper I (Geography), GS Paper III (Environment, Disaster Management)
Topics: Natural disasters, climate change, disaster management
Previous Year Questions:
Tropical cyclone formation and India's vulnerability (2021)
Climate change impact on cyclone intensity (2020)
Disaster management in coastal areas (2019)
Comparison of Bay of Bengal and Arabian Sea cyclones (2018)
Memory Techniques
Cyclone Formation Conditions: Sea Temperature Ocean Depth Wind Shear Coriolis
S - Sea surface temperature >26.5°C
T - Temperature warm water
O - Ocean depth >60m
D - Depth sufficient
W - Wind shear low
S - Shear minimal
C - Coriolis effect present
Cyclone Seasons: Pre-monsoon Monsoon Post-monsoon Winter
P - Pre-monsoon (Apr-May)
M - Monsoon (Jun-Sep) - Suppressed
P - Post-monsoon (Oct-Dec) - Peak
W - Winter (Jan-Mar) - Rare