It’s called the Fujiwhara effect after a Japanese meteorologist, Dr. Sakuhei Fujiwhara, who first described it in 1921. It’s a fascinating interaction between two nearby tropical cyclones (or other vortices like low-pressure systems). Here’s how it works: The Basics When two tropical cyclones form close enough to each other (usually within about 800–900 miles), their circulations begin to interact. Instead of moving independently, they start to rotate, or orbit, around a common center point betw