What is the reason for the continuous high temperature in recent days?

According to the weather bulletin of the Central Meteorological Observatory, in the past two days, China has experienced the largest range of high temperature weather since summer. Temperatures in the middle and lower reaches of the Yangtze River and most parts of South China, such as Shanghai, Zhejiang, Fujian and Chongqing, which are controlled by the subtropical high, have continuously refreshed the highest temperatures in the past 30 years, 60 years and the same period in history. People are very concerned about when the hot weather will ease. Zhou, deputy director of the weather forecasting office of the Central Meteorological Observatory, said that such high-temperature weather will not end in a short time, because the temperature will not change so fast, and there must be a process. He believes that the relief of high temperature weather in the south can only wait until the next typhoon brings rainfall. Up to now, the activities of the two typhoons "Swan" and "Ibudu" in the coastal areas of South China are relatively short this year, so the high temperature weather in Zhejiang, Fujian and Wuhan has not been effectively alleviated. Zhou said that the causes of persistent high temperature weather are complicated, but the direct cause of persistent high temperature weather is related to the subtropical high pressure system. Subtropical high is the main weather system that affects the change of summer rain belt and high temperature weather in China. The main reason for the continuous high temperature in the south this year is that typhoons frequently hit, and the subtropical high with rolling heat waves was forced to wander for a long time in the middle and lower reaches of the Yangtze River, thus forming a large-scale "steamer" weather. Zhou predicted that on the 30th, there will still be high temperature of 35-38 degrees Celsius in most parts of Huanghuai, Jianghuai, Hanshui River Basin, Jiangnan, north-central South China, Guizhou and Chongqing. Among them, the daily maximum temperature in some areas of Zhejiang, Fujian, Jiangxi, eastern Hunan, central and eastern Hubei, central and southern Anhui and other provinces can reach 39-4 1 Celsius. "The hot weather in the future is not optimistic." Zhou Dui said, "The drought will continue to spread in most parts of the south in the near future. While actively fighting drought in the south, we must prevent high temperature heatstroke. " (According to Xinhua News Agency, Beijing, July 29th)