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

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