Fujiwhara Effect

In News

• Recently, two cyclones, namely super typhoon Hinnamnor & tropical storm Gardo started hovering around the central line between them, showcasing the Fujiwhara Effect. 

About the Fujiwhara Effect

• Definition:
  • The Fujiwhara Effect is any interaction between tropical storms formed around the same time in the same ocean region with their centers or eyes at a distance of less than 1,400 km, with intensity that could vary between a depression (wind speed under 63 km per hour) and a super typhoon (wind speed over 209 km per hour).
• Propounder:
  • The Fujiwhara effect was identified by Sakuhei Fujiwhara, a Japanese meteorologist whose first paper recognising the Fujiwhara cases was published in 1921. 
• Known examples:
  • The first known instance of the effect was in 1964 in the western Pacific Ocean when typhoons Marie and Kathy merged.
• What it may lead to:
  • The interaction could lead to changes in the track and intensity of either or both storm systems. 
  • In rare cases, the two systems could merge, especially when they are of similar size and intensity, to form a bigger storm.
• There are five different ways in which the Fujiwhara Effect can take place. 
  • The first is elastic interaction: 
    • In this only the direction of motion of the storms changes and is the most common case. 
    • These are also the cases that are difficult to assess and need closer examination.
  • The second is partial straining: 
    • In this a part of the smaller storm is lost to the atmosphere.
  • The third is complete straining out: 
    • In this the smaller storm is completely lost to the atmosphere. The straining out does not happen for storms of equal strength.
  • The fourth type is partial merger: 
    • In this the smaller storm merges into the bigger one and 
  • The fifth is complete merger: 
    • It takes place between two storms of similar strength.
  • During a merger interaction between two tropical cyclones the wind circulations come together and form a sort of whirlpool of winds in the atmosphere.

Source: DTE