Cyclone Freddy travelled from Australia to batter Madagascar, one of the most climate-vulnerable nations
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Cyclone Freddy travelled from Australia to batter Madagascar, one of the most climate-vulnerable nations
Subject :Geography
Section: Physical geography
Context:
- Cyclone Freddy made landfall along Madagascar’s south-eastern coast.
Details:
- Madagascar was also hit by tropical storm Cheneso in January 2023.
- There were a total of six tropical weather systems (tropical storm Gombe on March 8 and tropical storm Jasmine on April 26), apart from the ITCZ, that affected Madagascar between January and April.
- Madagascar is also undergoing the worst famine in the recent history.
- The World Food Programme (WFP) called it the world’s first famine caused because of climate change.
About Cyclone Freddy:
- Freddy travelled around 7,200 km from the southeast Indian Ocean to Madagascar in 15 days.
- This is the first time since 2000 that a cyclone has moved such a long distance from the south-eastern parts to the south-western parts of the Indian Ocean.
- It is highly unusual for cyclones to be sustained for such long time periods and travel such long distances.
- The storm carried winds of 130 kilometres per hour at landfall and has brought torrential rainfall for south-eastern Madagascar.
- The cyclone is now moving towards Mozambique.
Role of Inter-tropical convergence zone (ITCZ):
- The rainfall started with an inter-tropical convergence zone (ITCZ) in mid-January.
- ITCZ is the region near the equator where the northeast and southwest trade winds converge to form a band of clouds with rainfall and occasional thunderstorms.
- The ITCZ gave way to two back-to-back tropical storm systems:
- tropical storm Ana in the last week of January.
- cyclone Batsirai in the first week of February.
Tropical cyclones:
- Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas.
- It brings large-scale destruction caused by violent winds, very heavy rainfall and storm surges.
- The winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Terminology:
- It varies location to location. They are known as
- Cyclones in the Indian Ocean
- Hurricanes in the Atlantic
- Typhoons in the Western Pacific and South China Sea, and,
- Willy-willies in the Western Australia.
Conditions favorable for the formation:
- Large sea surface with temperature higher than 27° C;
- Presence of the Coriolis force;
- Small variations in the vertical wind speed;
- pre-existing weak low-pressure area or low-level-cyclonic circulation;
- Upper divergence above the sea level system.
Characteristics:
- The energy that intensifies the storm comes from the condensation process in the towering cumulonimbus clouds, surrounding the centre of the storm.
- With continuous supply of moisture from the sea, the storm is further strengthened. The more time they spend over the seas, the stronger they become.
- On reaching the land the moisture supply is cut off and the storm dissipates. The place where a tropical cyclone crosses the coast is called the landfall of the cyclone.
- The cyclones, which cross 200 N latitude generally, re-curve and they are more destructive.
- A mature tropical cyclone is characterized by the strong spirally circulating wind around the centre, called the eye. The diameter of the circulating system can vary between 150 and 250 km. The eye is a region of calm with subsiding air.
- Around the eye is the eye wall, where there is a strong spiraling ascent of air to greater height reaching the tropopause. The wind reaches maximum velocity in this region, reaching as high as 250 km per hour. Torrential rain occurs here.
- From the eye wall rain bands may radiate and trains of cumulus and cumulonimbus clouds may drift into the outer region.
