Topic 1: Hazardous Earth Revision Notes

Formation and Characteristics of Tropical Cyclones

Tropical cyclones, also known as hurricanes or typhoons, originate over warm ocean waters (above 26.5°C). They are large, rotating storm systems with a central 'eye' of calm, clear weather. Key requirements for formation include warm sea surface temperatures, low wind shear, high humidity in the troposphere, and sufficient Coriolis effect for rotation. They draw energy from the evaporation of warm ocean water and release of latent heat through condensation, intensifying as long as they remain over these conditions. Wind speeds can exceed 119 km/h, with heavy rain and storm surges.

Hazards and Impacts on People and Places

The primary hazards associated with tropical cyclones include extreme winds, torrential rainfall leading to widespread flooding (riverine and flash floods), and devastating storm surges. Storm surges, often the most deadly aspect, are abnormal rises of water generated by the storm's winds and atmospheric pressure. These hazards cause substantial damage to infrastructure, destruction of homes, agricultural losses, contamination of water supplies, and significant loss of life. Long-term impacts can include economic disruption, displacement of populations, and ecological damage to coastal ecosystems.

Responses to Mitigate Cyclone Impacts

Responses to tropical cyclones involve both immediate actions and long-term planning. Short-term responses focus on prediction, monitoring, and warning systems (e.g., satellite tracking, weather buoys) to allow for timely evacuations and preparation. Long-term strategies include building codes designed to withstand strong winds, construction of sea walls and other coastal defences to mitigate storm surge, education and awareness campaigns, and community resilience programmes. Decisions about land use in vulnerable coastal areas are crucial for reducing risk. Evaluating these strategies helps assess their effectiveness.