INTRODUCTION

• Cyclone Montha, a tropical storm forming over the Bay of Bengal, is expected to make landfall between Kakinada and Machilipatnam in Andhra Pradesh.
• With wind speeds up to 80 kmph and heavy rainfall across coastal districts, it has already triggered large-scale evacuations—around 10,000 people relocated to relief camps.
• This event draws attention to the recurring challenge of cyclone preparedness and resilience along India’s eastern coastline.

WHAT IS A LANDFALL?

Definition and Process

• Landfall occurs when the eye (centre) of a tropical cyclone moves from the ocean onto the land surface.
• As per the India Meteorological Department (IMD):
  • Landfall is the point of intersection of the cyclone’s eye with the coastline.
  • It marks the transition of the cyclone from a marine to a terrestrial environment.

Clarifying Misconceptions

• Landfall vs. Direct Hit:
  • Landfall means the storm’s centre crosses the coast.
  • Direct hit refers to the eyewall (zone of highest winds) reaching the shore even if the centre remains offshore.
• Example: Strong winds can lash coastal areas even before landfall if the storm’s peripheral bands are wide.

METEOROLOGICAL FACTORS BEHIND A CYCLONE

• Formation Zone: Bay of Bengal and Arabian Sea—regions with warm sea surface temperatures.
• Driving Forces:
  • Warm ocean waters (>26°C) provide the energy source.
  • Low-pressure zone near the surface pulls in moist air.
  • Coriolis effect imparts rotation to the storm.
• Movement and Intensification:
  • Cyclones draw moisture from the sea and strengthen while over water.
  • Upon hitting land, they weaken rapidly due to loss of moisture supply and surface friction.

DAMAGE CAUSED BY LANDFALL

1. Wind Damage

• High-speed winds (80–150 kmph or more) uproot trees, electric poles, and damage structures.
• Kutcha houses and informal settlements are most vulnerable.
• Roofs, windows, and signboards often suffer extensive damage.

2. Storm Surge

• A storm surge is an abnormal rise in sea level accompanying a cyclone.
• It leads to:
  • Coastal inundation and erosion.
  • Contamination of freshwater sources with saline water.
  • Destruction of paddy fields and aquaculture.

3. Heavy Rainfall and Flooding

• Torrential rains trigger urban flooding, landslides, and crop loss.
• Low-lying areas experience stagnant water and vector-borne diseases post-cyclone.

4. Disruption of Infrastructure

• Power and communication lines collapse.
• Roads and railways face blockages.
• Airports and ports often suspend operations.

DURATION AND AFTERMATH OF LANDFALL

Duration

• Landfall typically lasts a few hours, depending on:
  • The speed of cyclone movement, and
  • The diameter of the storm system.
• Once over land, the cyclone weakens as:
  • Moisture supply reduces.
  • Surface friction increases.

Aftermath

• Despite weakening, post-landfall rainfall can persist for days.
• Relief and rehabilitation efforts must focus on:
  • Restoration of power and communication,
  • Water purification and sanitation, and
  • Psychosocial support for displaced populations.

PREPAREDNESS AND MITIGATION MEASURES

Government Response

• The National Disaster Response Force (NDRF) and State Disaster Management Authorities (SDMA) play key roles.
• Early warning systems by IMD enable evacuation and shelter planning.
• Relief camps are established in schools and government offices to ensure safety.

Community-Level Preparedness

• Awareness campaigns about cyclone alerts and evacuation routes.
• Training in first aid and rescue operations.
• Construction of cyclone-resilient housing in vulnerable districts.

Long-Term Strategies

• Mangrove restoration and coastal afforestation to reduce storm surge impact.
• Climate-resilient infrastructure in coastal zones.
• Integration of disaster management into local governance.

FORMATION OF CYCLONES

• Initial Stage:
  • Begins as a low-pressure area with clusters of thunderstorms.
  • Requires warm sea surface temperatures (>26.5°C, to 50 m depth).
• Energy Source:
  • Warm, moist air rises → releases latent heat → fuels convection.
  • This cycle strengthens the storm system.
• Atmospheric Conditions:
  • Unstable atmosphere: rising air continues upward.
  • Coriolis force: causes rotation; absent near the equator (within 5° latitude).
  • Low vertical wind shear: allows organized circulation to develop.
  • High wind shear: disrupts structure and weakens cyclones.

CYCLONE STRUCTURE

• Eye:
  • Calm, clear center of the storm.
  • Surrounded by the eyewall—a dense ring of towering thunderstorms.
• Eyewall:
  • Produces strongest winds and heaviest rainfall.
  • Air spirals inward at the surface, rises rapidly near the eyewall, and flows outward aloft.

 CYCLONE CLASSIFICATION

• Based on Wind Speed & Pressure:
  • North Indian Ocean (IMD system):
    • Depression: 31–49 km/h
    • Cyclonic storm: 63–88 km/h
    • Super cyclonic storm: >222 km/h

 MEASUREMENT TECHNIQUES

• Tools Used:
  • Ground observations, satellites, ocean buoys, aircraft reconnaissance.
  • Satellites: detect cloud-top temperature, structure, rainfall, and eye formation.
  • Aircraft (Hurricane Hunters): measure wind, pressure, humidity via dropsondes.
  • Indian Ocean: primarily uses satellite and buoy data.

 FORECASTING CYCLONES

• Methods:
  • Numerical weather models simulate ocean–atmosphere interactions.
  • Requires accurate initial data to minimize uncertainty.
• Accuracy:
  • Forecasts now predict cyclone track and intensity 3–5 days in advance.
  • Improvements driven by better computing power and remote sensing.

CONCLUSION

• Cyclone Montha’s landfall serves as a reminder of India’s climatic vulnerability and the need for robust preparedness systems.
• While technological forecasting and evacuation mechanisms have improved, sustainable coastal planning remains the key to minimizing loss of life and property.
• Strengthening community resilience and integrating climate adaptation into development planning must become national priorities in an era of intensifying tropical storms.

MAINS QUESTIONS

1. What is meant by the landfall of a cyclone? Explain how it differs from a direct hit.
2. Discuss the various forms of damage caused by a cyclone’s landfall with recent examples from India.
3. “Cyclones are both meteorological and socio-economic challenges.” Elucidate with reference to Cyclone Montha.

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