Tropical Cyclones: Formation and Structure

Tropical cyclones, also known as hurricanes or typhoons, are powerful storm systems that form over warm tropical waters. They only develop in areas where sea surface temperatures exceed 26.5°C, typically occurring during summer and early autumn.

Vocabulary: Tropical cyclones are intense low-pressure systems characterized by strong winds and heavy rainfall.

Key characteristics of tropical cyclones include:

1. Low-pressure center
2. Warm, moist air rising through the atmosphere
3. Rotation influenced by the Earth's spin

The structure of a tropical cyclone consists of a cylinder of rising, spiraling air that can reach up to 10 km in height and 640 km in width.

Highlight: Tropical cyclones move westward due to easterly winds and spin away from the equator.

Saffir-Simpson Scale and Cyclone Formation

The Saffir-Simpson Scale categorizes tropical cyclones based on their intensity:

1. Category 1: Some damage to trees, roofs, and windows
2. Category 2: Moderate damage
3. Category 3: Structural damage to buildings and flooding
4. Category 4: Major destruction of buildings and severe flooding
5. Category 5: Catastrophic damage

Tropical cyclones form under specific conditions:

1. Warm sea temperatures $above 26.5°C$
2. High humidity with abundant moisture
3. Rapid cooling of rising air to generate energy

Factors that intensify or weaken tropical cyclones:

• Sea surface temperatures above 26.5°C
• Low wind shear
• High humidity
• Landfall $causes weakening due to loss of energy source$
• Movement into areas with colder water

Impacts and Secondary Hazards of Tropical Cyclones

Tropical cyclones can cause significant damage and loss of life. Secondary hazards associated with these storms include:

• Storm surges
• Landslides
• Coastal flooding

Example: Hurricane Katrina in 2005 caused $108 billion in damage and resulted in 1,836 deaths.

Storm surges occur when cyclones push water towards the coast, causing sea levels to rise dramatically. Coastal flooding and landslides are often triggered by heavy rainfall, with deforestation exacerbating these risks.

Dealing with Tropical Cyclones

Advanced weather forecasting and satellite technology play crucial roles in managing tropical cyclones. These tools allow meteorologists to:

• Detect cyclone formation
• Track storm progress
• Predict storm intensity and rainfall levels

Factors affecting a country's vulnerability to tropical cyclones include:

1. Physical: Low-lying coastal areas are more susceptible to damage
2. Social: Poor communities often suffer more due to inadequate housing
3. Economic: Developed countries have better prediction, protection, and evacuation capabilities

Strategies to help people during tropical cyclones:

• Government-issued evacuation instructions
• Timely predictions and warnings
• High-ground shelters in surge-prone areas
• Public education on evacuation preparedness

Case Study: Hurricane Katrina (USA, 2005)

Hurricane Katrina, a Category 3 storm when it made landfall, struck the United States in August 2005. This powerful tropical cyclone caused 1,836 deaths, primarily in New Orleans.

Highlight: The high death toll was largely due to failures in storm surge defenses and flooding of pumping stations.

This case study demonstrates the devastating impact that tropical cyclones can have even in developed countries with advanced warning systems and infrastructure. It underscores the importance of maintaining and improving flood defenses and evacuation procedures in vulnerable coastal areas.

Tropical Cyclone Impacts and Secondary Hazards

Secondary hazards associated with tropical cyclones include:

1. Storm surges
2. Landslides
3. Coastal flooding

Example: Hurricane Katrina caused $108 billion in damage and 1,836 deaths.

Storm surges:

• As cyclones approach the coast, water is pushed up onto land due to shallower sea depths.

Coastal flooding and landslides:

• Heavy rainfall causes flash flooding and triggers landslides, often exacerbated by deforestation.

Dealing with tropical cyclones:

1. Weather forecasting and satellite technology
2. Tracking cyclone formation and progress
3. Predicting storm height and rainfall levels

Quote: "Hurricane Katrina caused $108 billion of damage and 1,836 deaths."

Vulnerability Factors and Mitigation Strategies

Factors affecting a country's vulnerability to tropical cyclones:

1. Physical: Low-lying coastal areas $e.g., Pacific islands$
2. Social: Poor areas often hit harder due to substandard housing
3. Economic: Developed countries have better prediction, protection, and evacuation technologies

Strategies to help people:

1. Government evacuation instructions
2. Informed predictions and warnings
3. High-ground shelters in surge-prone areas
4. Education on evacuation preparation

Highlight: Rich, developed countries are generally less vulnerable to tropical cyclones due to better infrastructure and resources.

Case Study: Hurricane Katrina (USA)

• Occurred in August 2005
• Category 3 when it made landfall
• 1,836 deaths, mostly in New Orleans
• Deaths primarily due to failures in storm surge defenses
• Pumping stations were flooded and failed to work
• Evacuation problems contributed to the high death toll

Example: Hurricane Katrina demonstrated the importance of robust infrastructure and effective evacuation procedures in mitigating the impacts of tropical cyclones.

Natural Causes of Climate Change

Natural causes of climate change include Milankovitch cycles and volcanic eruptions. The Earth experiences alternating periods of ice ages $glacial periods$ and warmer interglacial periods, with the current era being an interglacial period.

Definition: Milankovitch cycles refer to the changes in Earth's orbit that occur approximately every 100,000 years, affecting the planet's climate.

Volcanic eruptions can cause temporary cooling by releasing ash and dust into the atmosphere. Ocean currents also play a role in climate regulation, with shifts potentially leading to cooler climates for short periods.

Highlight: We currently enjoy a warm and wet climate due to Atlantic currents, but shifts in these currents can result in temporary cooling.

Human Impact on Climate Change

Human activities significantly contribute to climate change through industries, transportation, farming, and energy production. These sectors release CO₂, leading to global warming and the enhanced greenhouse effect.

Vocabulary: The enhanced greenhouse effect occurs when human activities increase the concentration of greenhouse gases in the atmosphere, trapping more heat and causing global warming.

Evidence of climate change includes:

• Rising sea levels
• More frequent extreme weather events
• Warming oceans
• Increasing CO₂ levels correlating with global temperature rise

Consequences of climate change, primarily driven by human activities, include:

• Biodiversity loss in terrestrial and marine ecosystems
• Coastal flooding due to rising sea levels
• Spread of diseases
• Loss of glaciers leading to water supply issues