Fujiwhara Effect, Meaning, Impact, Examples in India and World

The Fujiwhara Effect is a weather phenomenon in which two nearby cyclones interact and influence each other’s movement or intensity. It was first described by Japanese meteorologist Dr. Sakuhei Fujiwhara in 1921. The interaction occurs when tropical cyclones come within about 1,400 km of each other. It can alter cyclone tracks and, in rare cases, cause the storms to merge.

What is the Fujiwhara Effect?

The Fujiwhara Effect occurs when two cyclonic systems form close enough for their circulations to interact. The effect is also called Fujiwhara interaction or binary interaction.

• Cyclone Distance: Tropical cyclones generally show this interaction when their centres are less than 1,400 km apart. Extratropical cyclones can interact within 2,000 km.
• Common Centre: The two cyclone centres orbit a point between them in a counterclockwise direction. The smaller cyclone usually moves faster around this point.
• Possible Outcomes: The interaction can change cyclone tracks, alter intensity, divert one or both systems, or cause merging. Similar-strength cyclones have greater potential to merge.

Impact of Fujiwhara Effect on the Movement and Intensity of Tropical Cyclones

The Fujiwhara Effect can significantly modify the movement, direction and intensity of nearby tropical cyclones. Its impact depends mainly on the distance, relative size and strength of the interacting systems.

• Change in Movement: Two nearby tropical cyclones begin orbiting a common point when they interact. Their paths can bend, stall, accelerate or shift from the original forecast direction.
• Effect of Relative Strength: When cyclones differ greatly in size or intensity, the stronger system usually dominates the interaction. The smaller cyclone tends to move faster around the larger system.
• Acceleration of Interaction: The interaction becomes stronger as cyclones approach each other. Their rotation around the common centre accelerates when they come within about 650 km of each other.
• Change in Intensity: The interaction can strengthen one cyclone while weakening the other. For example, Hurricane Hilary intensified while Hurricane Irwin weakened during their 2017 interaction in the East Pacific Ocean.
• Merging or Dissipation: When two systems approach within about 300 km, one may merge with the other or become sheared apart. Similar-sized and similarly intense cyclones can also combine into one larger cyclone.

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Fujiwhara Effect Examples in India and World

The Fujiwhara Effect has been observed in several tropical cyclone interactions globally.

• 1964 Western Pacific: Typhoons Marie and Kathy interacted and eventually merged, providing an early observed example of the phenomenon.
• Hinnamnor and Gardo: Meteorologists observed Fujiwhara interaction between Typhoon Hinnamnor, known in the Philippines as Super Typhoon Henry, and tropical storm Gardo.
• Bay of Bengal: In 2022, two cyclonic storms were predicted to form in the Bay of Bengal, raising the possibility of a Fujiwhara interaction between the systems

UPSC Mains Question 2026 

What is the Fujiwhara effect? Explain its impact on the movement and intensity of tropical cyclones.