Fujiwhara effect

The effect is named after Sakuhei Fujiwhara, the Japanese meteorologist who initially described it in a 1921 paper about the motion of vortices in water.

[4][5] Tropical cyclones can form when smaller circulations within the Intertropical Convergence Zone merge.

[6] The effect is often mentioned in relation to the motion of tropical cyclones, although the final merging of the two storms is uncommon.

Rotation rates within binary pairs accelerate when tropical cyclones close within 650 kilometres (400 mi) of each other.

[9] The precise results of such interactions depend on factors such as the size of the two cyclones, their distance from each other, and the prevailing atmospheric conditions around them.

Typhoon Parma (left) and Melor (right) interacting with each other in the Philippine Sea on October 6, 2009.
Diagram of the Fujiwhara effect, showing how 2 tropical cyclones interact with each other. [ 1 ]
Odette (left) and Seroja (right) engaged in a Fujiwhara interaction whilst intensifying between 7–9 April 2021.
This satellite loop covering April 26–28, 2011 shows two extratropical cyclones involved in Fujiwhara interaction across the Midwest and Great Lakes.