Tropical cyclone hazards: distribution, processes, impacts, management

Distribution

🌍 Tropical cyclones form over warm ocean waters (≥26.5 °C) between 5° N–5° S and 5° N–30° N. They are most common in the North Atlantic, Western Pacific, Indian Ocean, and South Pacific.

Exam Tip

Remember: “Where warm ocean + low pressure + Coriolis force” = cyclone. Use the mnemonic WALC to recall the conditions.

Processes

Think of a cyclone as a giant spinning vacuum cleaner that pulls in warm, moist air from the ocean surface.

1. Warm air rises at the centre, creating a low‑pressure zone.
2. Air rushes in from the sides, gaining speed due to the Coriolis effect, which turns the flow counter‑clockwise in the Northern Hemisphere.
3. Condensation releases latent heat, further warming the core and intensifying the storm.
4. The system moves westward along the trade winds, then curves poleward as it loses energy.

Key formula: kinetic energy of wind $E_k = \tfrac{1}{2}\rho A v^3$, showing how a small increase in wind speed dramatically increases energy.

Impacts

• 🌊 Storm surge – seawater pushed onto land, flooding low‑lying areas.
• 💨 Wind damage – trees uprooted, roofs torn off.
• 🌧️ Heavy rainfall – flash floods, landslides.
• 🌪️ Secondary hazards – power outages, disease outbreaks.

Analogy: Imagine a giant water‑splashing roller coaster that throws everything in its path.

Management

Effective management mixes prediction, preparedness, and response.

1. 🌐 Forecasting – satellite imagery, radar, and computer models predict path and intensity.
2. 🏠 Evacuation plans – clear routes, shelters, and communication.
3. 🚑 Emergency services – pre‑positioned supplies, rapid response teams.
4. 🛠️ Infrastructure resilience – building codes, seawalls, and drainage systems.

Exam tip: Use the “5 W’s” – Who, What, When, Where, Why – to structure answers on cyclone management.