Why in the news?
- The IMD has forecast the formation of two cyclonic storms in the Bay of Bengal, which may undergo a Fujiwhara interaction.
Fujiwhara Effect
- What is it?: The Fujiwhara Effect describes the interaction between two nearby cyclonic systems (tropical cyclones, depressions, or vortices) in which they begin to rotate around a common centre.
- Occurrence: It happens when,
- Two cyclonic systems come within ~1,000 km of each other (threshold varies with storm size/strength).
- Both systems are strong enough to influence each other’s circulation.
- Types of Fujiwhara Effect:
- Mutual Orbiting:
- The cyclones revolve around a common pivot point.
- Typically, both rotate counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
- Absorption / Merger: A stronger cyclone may absorb the weaker one.
- Deflection: Interaction may redirect one or both cyclones away from their expected tracks.
- Mutual Orbiting:
- Effects
- Unpredictable movement forecasting becomes challenging.
- Possible rapid intensification or weakening, depending on energy transfer.
- Can lead to changes in rainfall distribution and landfall location.
- In rare cases, it can produce super cyclonic behaviour if environments are favourable.
- Examples
- In 2017, East Pacific Hurricanes Hilary and Irwin orbited each other, with Hilary strengthening as Irwin weakened and changed course.
- 2025 Atlantic Hurricanes Imelda and Humberto interacted, marking a rare occurrence in that basin; another potential case involved Humberto and a Caribbean low.
Source: Down To Earth