Typhoons rarely visit Shanghai. Why?

Shanghai is in the middle of Jiangsu and Zhejiang as a whole, but compared with Jiangsu and Zhejiang, the number of typhoons in Shanghai is really less, which is related to the length of Shanghai coastline and the latitude where Shanghai is located. Therefore, typhoons landing along China's coast are often ridiculed as having no "Shanghai brand".

First of all, let's look at the length of Shanghai's coastline. Although it is not particularly short as a single city, especially with Chongming Island, it makes Shanghai's coastline second to none among all cities in China. However, among all the provinces and regions in the southeast coast, the vertical crossing of Shanghai's coastline from north to south is the shortest, which reduces the probability of typhoon landing, just like "shooting". This reason is purely numerical probability difference, which is easy to understand.

another reason is the latitude of Shanghai, which is between 3 4 ′ and 31 53 ′ north latitude, and 3 ′ north latitude is the dividing line between low-latitude circulation and mid-latitude circulation. The low-latitude circulation produces easterly belt, while the mid-latitude circulation produces westerly belt. The typhoon affecting China is basically formed in the equatorial low latitude area, and in the process of advancing to the northwest, it meets the westerly belt at 3 degrees north latitude, so the typhoon will turn northeast in this area, just bypassing Shanghai.

finally, according to the meteorological data of previous years, the probability of typhoon landing in Zhejiang and Fujian in the south of Shanghai is greater, because the cyclone energy generation has a great relationship with latitude and temperature during the process of typhoon landing in China. In normal meteorological years, the typhoon has basically turned westward at low latitudes, affecting Zhejiang and Fujian. However, when the climate is abnormal, the latitude of the subtropical ridge line rises, and it is only when the typhoon turns westward that it is likely to go straight to Shanghai.

It should have a lot to do with the latitude of Shandong Peninsula and the depth of the sea. Because in the whole Bohai Bay, the average seawater depth is less than 1 meters, and most seawater depths are only about 5 to 6 meters deep. Such a depth of sea water, even if typhoons and storm surges come, will be slightly weakened because of the low depth of sea water.

plus the latitude (north), typhoons are mostly generated in the south (Philippines, northern South China Sea). The typhoon swept all the way from south to north. When it arrived in Shandong, it had been greatly weakened. Even if it was strengthened, it was a rare occurrence in a hundred years, and it would be weakened by the low water depth in the Bohai Bay.