Cyclone Alfred

Why in News?

Recently, Cyclone Alfred struck the eastern coast of Australia, causing widespread devastation. It was one of the most dangerous storms in the region in the past 50 years. Its maximum recorded wind speed reached 130 km/h.

What is Cyclone Alfred?

Cyclone Alfred is a tropical storm that has recently struck the eastern coast of Australia. 

• It has formed farther south than usual and is moving slowly, increasing its potential impact over a prolonged period. 
• This cyclone is expected to affect densely populated areas such as Brisbane, Gold Coast, Sunshine Coast, Byron Bay, and Ballina. 
• It may bring strong winds, heavy rainfall, and flooding. 
• The last cyclone of similar strength in this region occurred in 1974, causing widespread destruction. 
• Cyclone Alfred poses a significant threat from Double Island Point (Queensland) to Grafton (New South Wales) due to its slow movement and unusual formation.

Main Reasons for Cyclone Alfred’s Slow Movement

Cyclone Alfred is moving slower than typical cyclones, which increases its impact over a prolonged period. The primary reason for its slow movement is atmospheric conditions that are influencing its path and intensity.

• High-Pressure System: A strong high-pressure system over the Tasman Sea is affecting the cyclone’s trajectory. This system is blocking easterly winds, preventing Alfred from moving forward at a faster pace. As a result, it is being pushed westward toward densely populated areas, increasing the potential risks.
• Weak Steering Winds: Cyclones are usually guided by steering winds, which help them move in a particular direction. However, these winds are currently weak, causing Alfred to linger in one area for an extended period. The lack of strong guiding winds is preventing the cyclone from moving quickly.

Impacts of a Slow-Moving Cyclone

• Heavy Rainfall and Flooding: Slow-moving cyclones dump excessive rainfall in a single area, leading to severe flooding and waterlogging. Initially, Alfred was expected to pass quickly, but its prolonged presence is worsening the flood situation.
• Intensification of Ocean Waves: As a cyclone stays near the coast for an extended time, ocean waves grow larger, leading to coastal erosion. This can damage residential and commercial structures along the shoreline and disrupt fishing and navigation activities.
• Climate Change: Rising sea surface temperatures are affecting the formation and intensity of cyclones. Due to climate change, cyclones are now impacting areas that were not previously prone to such storms. This has widespread effects on agriculture, water supply, infrastructure, and marine ecosystems.
• Tropical Cyclones: Conditions, Naming, and Impact

Tropical cyclones are violent storms that originate over oceans and move toward coastal areas, causing widespread destruction due to strong winds, heavy rainfall, and storm surges. Several factors influence their direction and intensity, leading to regional variations in their characteristics.

• Different Names: Tropical cyclones are known by different names in various oceanic regions:
  • In the Indian Ocean, they are called Cyclones.
  • In the Atlantic Ocean, they are known as Hurricanes.
  • In the Western Pacific Ocean and the South China Sea, they are termed Typhoons.
  • Along the western coast of Australia, they are called Willy-Willies.
• Favorable Conditions: 
  • Sea surface temperature must be above 27°C, providing the necessary heat and moisture for cyclone development.
  • The presence of the Coriolis force, which results from Earth’s rotation and helps determine the cyclone’s direction.
  • Low vertical wind shear, ensuring the storm’s organized structure and allowing it to intensify.
  • A pre-existing low-pressure area or cyclonic circulation, which serves as the initial disturbance for cyclone development.
  • Upper atmospheric divergence, which helps sustain the low-pressure system by drawing air upward.
  • Cyclones gain strength as long as they receive moisture and energy from the sea. However, once they make landfall, their moisture supply is cut off, leading to their gradual weakening.
• Structure: A fully developed tropical cyclone consists of the following components:
  • Eye: The calm center of the cyclone, where pressure is the lowest. It typically ranges from 150 to 250 km in width.
  • Eye Wall: The most dangerous part of the cyclone, where winds reach up to 250 km/h due to intense upward movement of air.
  • Spiral Bands: Bands of clouds and rainfall that spiral around the cyclone, contributing to its overall energy and strength.
• Naming Process: Naming cyclones is crucial for easy identification and communication during warnings and forecasts.
  • Regional Specialized Meteorological Centers (RSMCs) and Tropical Cyclone Warning Centers (TCWCs) are responsible for naming cyclones in different ocean basins.
  • There are six RSMCs and five TCWCs worldwide, including the India Meteorological Department (IMD).
  • The IMD assigns names for tropical cyclones in the region and issues advisories for 13 countries, including India, Bangladesh, Sri Lanka, and Thailand.
• Impacts: 
  • Landfall: When a cyclone hits the land, it is called landfall. During this phase, strong winds and heavy rainfall can lead to flooding and destruction.
  • Cyclone Recurvature: Most cyclones change direction after crossing 20°N latitude, making them more destructive as they interact with land and atmospheric systems.
  • Coastal Erosion: Cyclones increase ocean wave intensity, leading to severe coastal erosion. This can damage coastal settlements, infrastructure, and ecosystems.
  • Cyclone Patterns: Due to climate change, the intensity and frequency of cyclones are increasing. Rising sea surface temperatures are fueling stronger storms, and unusual weather patterns are causing cyclones to impact previously unaffected regions.

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