The fury of nature: A guide to cyclones, hurricanes & tornadoes
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Differences between hurricanes, cyclones and tornadoes
Feature | Hurricane / cyclone / typhoon | Tornado |
Definition | Large-scale low-pressure systems with organised thunderstorms over warm oceans | Small, intense vortex column formed over land or water |
Size | 150-1,000 km in diameter | 100-500 metres wide (localised) |
Duration | Days to over a week | Few minutes to an hour |
Wind Speed | 120-250 km/h or more | Up to 480 km/h |
Formation Area | Over tropical oceans | Mostly over land in mid-latitudes |
Other names | Called cyclones (Indian Ocean), Typhoons (NW Pacific), Hurricanes (Atlantic & NE Pacific) | Called tornadoes worldwide |
Impact | Widespread: flooding, storm surge, wind | Localised but extremely destructive |
Structure | Eye, eye wall, spiral rain bands | Funnel-shaped rotating column |
Cyclone naming system
Cyclones are named to improve communication and avoid confusion. Naming is done by regional meteorological organisations such as the IMD (India Meteorological Department) for the North Indian Ocean.
Naming rules
- Purpose of naming: To simplify communication, avoid confusion during multiple storms and raise public awareness.
- Who names them: Regional Specialised Meteorological Centres (RSMCs) and Tropical Cyclone Warning Centres (TCWCs) under the World Meteorological Organization (WMO).
- Naming criteria: Names must be short, easy to pronounce and culturally appropriate.
- They should not be offensive, politically sensitive or repeated.
- Each region maintains its own pre-approved list of names.
- Regional lists: For the North Indian Ocean, the India Meteorological Department (IMD) assigns names from a list contributed by 13 countries, including India, Bangladesh, Oman and others.
- In the Atlantic, names rotate every six years unless retired due to severe impact.
- Order of use: Names are used sequentially from the list. Once a name is used, it is not reused in that region.
- Retirement of names: If a cyclone is particularly deadly or costly, its name is retired and replaced to avoid future distress.
Notable destructive cyclones
Worldwide:
• Typhoon Haiyan (2013) – Philippines; over 6,300 dead.
• Hurricane Katrina (2005) – USA; Rs $125 billion in damages.
• Cyclone Nargis (2008) – Myanmar; Rs 1,40,000 deaths.
• Super Typhoon Tip (1979) – Largest ever recorded.
India:
• 1999 Odisha Cyclone – Over 10,000 deaths.
• Cyclone Amphan (2020) – Rs $13 billion in damages.
• Cyclone Tauktae (2021) – Western coast, major infrastructure loss.
• Cyclone Fani (2019) – Odisha; extensive evacuations minimised casualties.
Cyclone formation & structure
Formation process
- Warm ocean water (≥27 degrees C) provides energy.
- Air rises due to heating; creates low pressure.
- More moist air rushes in, forming a vertical convection system.
- Coriolis force (due to Earth’s rotation) causes rotation.
- A cyclonic vortex develops; wind spirals inward and upward.
Structure of a tropical cyclone
Key parts
- Eye: Calm center (20–50 km); low pressure.
- Eyewall: Strongest winds, intense rain.
- Spiral Bands: Curved clouds with heavy rain, thunderstorms.
UPSC-style questions
🔹 Short answer questions
- What are the different regional names for tropical cyclones?
- What is the role of the Coriolis force in cyclone formation?
- Mention two destructive cyclones that affected India.
🔹 Long answer questions
- Explain the structure and mechanism of formation of a tropical cyclone.
- Differentiate between tropical cyclones and tornadoes in terms of origin, structure, and impact.
- Discuss the naming system of cyclones in the North Indian Ocean region.
🔹 Analytical/essay type
- “Cyclones are natural but their destructiveness is increasingly human-made.” Critically examine with examples.
- Discuss how climate change is impacting the frequency and intensity of tropical cyclones in the Indian Ocean region.
- What disaster management strategies should be adopted to mitigate cyclone impacts in coastal India?
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