Tropical Storms (Cambridge International IGCSE Geography)

Specification link

This page covers sections 2.3.4 and 2.3.5 of the CIE IGCSE Geography specification.

• 2.3.4- The distribution and impacts of tropical storms: cyclones, hurricanes, and typhoons.
• 2.3.5 - An evaluation of the strategies and techniques used to manage the impacts of tropical storms: preparation, planning, protection, and prediction.

Tropical storm distribution

Spec point — The distribution and impacts of tropical storms: cyclones, hurricanes, and typhoons

• Tropical storms are rotating, intense low-pressure systems (below 950mb)

• They are known as:

  • Typhoons in the South China Sea and west Pacific Ocean
  • Hurricanes in the Gulf of Mexico, Caribbean Sea and west coast of Mexico
  • Cyclones in the Bay of Bengal, Indian Ocean and northern Australia

Distribution of tropical storms

• Tropical storms need specific conditions to form

  • Ocean temperatures must be in excess of 27°C and to a depth of 50-60 metres
  • Between 5° and 30° north and south of the equator, but not on the Equator, as there is no Coriolis effect

• Tropical storms begin when tropical oceans are at their warmest, which is usually late summer (Nov-April in the southern hemisphere and June-Nov in the northern hemisphere)

  • The Pacific Ocean sees the largest number of tropical storms, followed by the Indian Ocean, and lastly, the Atlantic
  • Tropical storms in the western Pacific are the strongest

Characteristics of tropical storms affect impacts

• Characteristics include:

  • lasting 7-14 days
  • large diameter
  • heavy rainfall
  • high wind speeds (over 119 km/h)
  • high waves and storm surges

• Tropical storms can vary in diameter (100 and 1000 km) but generally ranges from 200 to 500 km (124 to 311 miles)

• The winds of the storm are not constant across its diameter

  • The outer edges of the storm have lighter wind speeds, smaller and more scattered clouds, less intense rain, and temperatures begin to increase
  • The strongest and most destructive winds are found within the eyewall, with spiralling storm clouds, torrential rainfall and low temperatures

• Tropical storms are rated on the five-point Saffir-Simpson scale based on wind speeds

• Tropical storms are considered major when they reach category 3 and have wind speeds between 111 and 129 miles (178 and 208 kilometres) per hour

• A category 5 storm can deliver wind speeds of more than 157 miles (252 km) an hour

Impacts of tropical storms

• The primary impacts of tropical storms

  • High winds up to 250 km/h uprooting trees, damaging infrastructure and buildings, causing injury and loss of life
  • Intense rainfall leading to flash flooding, damaging property and injuring people from fast-flowing water
  • Storm surges from large areas of low pressure allow the sea level to rise, which, combined with high winds, forces a large mass of water towards land. This erodes beaches, damage sea defences and contaminates farmland and freshwater
  • Coastal flooding caused by intense rainfall and storm surges can affect large areas of low-lying land, including farmland and the tourist industry
  • Landslides are triggered because soil becomes saturated due to intense rainfall and in areas with steep slopes, where the soil can no longer hold its position, sliding down the slope

• The secondary impacts of tropical storms include

  • People are made homeless, causing distress, poverty, ill health or death due to a lack of shelter. The cost of rebuilding can be expensive and some people may not have insurance

  • Blocked or destroyed roads prevent rescue and emergency vehicles, and aid from getting through

  • Life support systems, hospitals, shops and homes left without power supplies when electricity lines are damaged/destroyed

  • There are risks of fires and explosions as gas lines are broken

  • Clean water supplies are contaminated as sewage overflows, bringing the increased risk of waterborne diseases and death

  • Economic impact to business owners and potential unemployment as businesses are destroyed

  • Storm surge can drown people or cause injuries from the rushing water. Crops, livestock and habitats are destroyed, leading to a shortage of food and potentially famine

    • For instance, Cyclone Idai destroyed almost 715,000 hectares of crops in March 2019, resulting in food shortages in Mozambique
    • The cyclone killed over 1,000 people and affected over 15 million in Mozambique, Malawi, and Zimbabwe
    • It was the second-deadliest tropical cyclone ever seen in the southern hemisphere

Exam Hint The storm's impact increases with the number of settlements and businesses, affecting more people and properties.

Planning, preparation, protection, and prediction of tropical storms

Spec point — An evaluation of the strategies and techniques used to manage the impacts of tropical storms: preparation, planning, protection, prediction.

• The level of preparation depends on accurate forecasting and then communications but also level of development

• High-income countries (HICs) are able to spend money on preparation and high-tech systems of prediction and notification

• Middle-income countries (MICs) and low-income countries (LICs) may find it difficult to buy satellites and monitoring systems or communicate the information to people likely to be affected

• The 4 P's are used to manage tropical storms: planning, preparation, protection, and prediction(for the future)

• These aim to:

  • Save lives
  • Protect personal property and infrastructure

• Planning provides long-term strategies to mitigate the impacts of tropical storms

  • Examples include building homes and businesses away from high-risk areas, such as the coast

  • Implement building standards to ensure structures can withstand hurricane-force winds and storm surges

    • Areas of poverty lead to poor construction of housing, which is more easily damaged: regardless of level of development

• Preparation involves taking measures to minimise risks and ensure readiness before a tropical storm strikes

  • Examples include developing emergency response plans

  • Stockpiling supplies and advising people to maintain a survival kit

  • Educating residents about evacuation routes and safety procedures

  • Reinforcing buildings and securing loose objects that could become projectiles in high winds are also sensible preparations

    • People who know how to react are more likely to survive, as they will evacuate safely
    • Survival kits can help those who are trapped to survive whilst waiting for help

• Protection involves creating structures that help lessen the effects of tropical storms on both people and property

  • This includes things like building seawalls, levees, and storm surge barriers that can prevent flooding

  • Mangroves are nature's own defence system and can play a crucial role in reducing the impacts of storm surges and coastal erosion when planted

    • Buildings are less likely to be destroyed, so less people will die from collapsing buildings and falling debris
    • Buildings will not be flooded This reduces the risk of flooding from overflowing rivers, or from storm surges

• Prediction is understanding where the storm is headed and how strong it’s going to be

  • Early warning systems alert those who are at risk

  • Meteorological agencies combine satellite imagery and weather models with historical data to predict how tropical storms will develop and move

    • This allows time for evacuation, which will reduce the number of deaths and injuries
    • It also means people can protect their homes and businesses from strong winds and flooding