How did the strange typhoon path come about, traveling at right angles and in a large V shape?

According to statistics, an average of 11.38 typhoons are generated each year. In autumn, the number of typhoons generated is usually comparable to that in summer. According to the medium-term forecast of the Central Meteorological Observatory, from September 25 to October 5, two or three typhoons will be generated in the South China Sea and the northwest Pacific Ocean, named "Little Dog", "Bolaven" and "Sanba" respectively. Turning, turning around, circling, and even taking V-shaped, Z-shaped, and serpentine routes, the various strange ways of typhoons make typhoon path prediction a difficult point.

Typhoon plays various weird moves

In June this year, Typhoon Mawar suddenly turned and headed for Japan when it was about to land on my country's coastline. It is not uncommon for typhoons like this to change direction and head for South Korea and Japan when they were about to land on my country.

Of course, some typhoons do not turn so smoothly, but rather sharply. Typhoon Fireworks in 2021 and Typhoon Xuanlannuo in 2022 both made sharp turns of less than or close to 90 degrees. After this year's No. 5 typhoon Dusurui developed into a super typhoon in July, it suddenly made four consecutive right-angle turns, which was a rare situation.

Not only that, many typhoons have many strange ways of moving, not only turning, but also turning around, circling, and even taking V-shaped, Z-shaped, and serpentine paths. From the end of August to the beginning of September 2022, the 11th super typhoon "Xuan Lannuo" took a unique V-shaped path, which was the first record since the typhoon was recorded. The typhoon swung back and forth while moving forward, forming a serpentine path. Every swing of it may cause confusion in the forecast conclusion, or constantly change the forecast conclusion according to the actual situation.

Typhoon "Jasper" No. 12 in 2018 was like a roller coaster ride from the moment it formed. It first made a big circle and drew a "question mark", then circled around in circles on the sea, approached the eastern coast of my country, and finally drove straight into the inland of my country.

In 1986, Typhoon Wayne experienced two strengthening and weakening processes in its 21-day life cycle, and its path changed significantly five times, including many U-turns and even four 180-degree sharp turns. Such a tortuous path is rare. Typhoons Nader in 1991 and Lily in 2001 also loved to turn around.

Mainly affected by complex atmospheric environmental factors

As a strong tropical cyclone that occurs in the northwest Pacific Ocean and the South China Sea, typhoons can form all year round, usually from May to December, but often in summer and autumn, especially from July to September when the largest number of typhoons are formed. After forming, typhoons generally move out of their source and go through an evolutionary process of development, weakening, and extinction. The typhoon path refers to the path that the typhoon takes during this process.

In fact, typhoon paths can be divided into conventional paths and unconventional paths. Sometimes they follow conventional routes, which can be roughly divided into three categories: westward-moving typhoons, landfalling typhoons, and turning typhoons. Westward-moving typhoons move westward from the east of the Philippines, pass through the South China Sea, and finally land on Hainan Island or northern Vietnam; landfalling typhoons move northwestward from their source, mostly landing on the coasts of Taiwan, Fujian, and Zhejiang. This type of typhoon has the greatest impact on my country; turning typhoons move northwestward first, and when they approach my country's eastern coastal areas, they do not land but turn to the northeast, or even turn to the vicinity of Japan, with a parabolic path. The unconventional paths of typhoons are mainly various strange ways of moving, which can be said to be varied and each showing its magical powers.

The reasons for the diversity of typhoon paths are very complicated, but it is mainly because typhoons are affected by complex atmospheric environmental factors during their atmospheric movement. Among them, systems such as the subtropical high pressure and the westerly belt will affect the path selection of the typhoon. After the typhoon is generated, its movement is mainly pulled by the Pacific subtropical high pressure. At first, the typhoon was generated in a relatively southern position, and was affected by the easterly wind from the south and moved westward; when it reached a higher latitude, due to the increase in the Coriolis force, it began to move northward and was gradually affected by the westerly belt, turning to the east. At the same time, it is also affected by other typhoons. When two or more typhoons that are close to each other interact, they often "pull and tug" at each other, causing the path to change.

(The author Li Gengtuo is a member of the Hunan Science Writers Association)