In the Battle of Chibi, what is the principle of the east wind borrowed by Zhuge Liang?

Zhuge Liang borrowed the Battle of Chibi from the history of Dongfeng. The general process is: in July of the 13th year of Jian'an, Cao Cao went south to Jingzhou in August. Liu Biao, a herdsman in Jingzhou, died, and his youngest son Liu Cong succeeded to the throne and settled in Xiangyang. In September, when Cao Cao arrived in Xinye, Liu Bei was stationed in the vassal city, and Liu Cong won without a fight. Liu Bei hurriedly retreated south and lost the mouth of the gorge. In October, Cao Cao marched to Jiangling to conquer the south of the Yangtze River, and Zhuge Liang sent an envoy to the east of the Yangtze River. Sun Quan decided to unite with Liu Kangcao, appointing Zhou Yu and Cheng Pu as the left and right supervisors, and Lu Su as the captain of Zanjun's school. From November to December, he joined Liu Bei's army and entered Chibi. The Sun Quan and Liu coalition fought against Cao's army in Chibi for the first time.

Cao Jun was defeated and retreated to the Wulin District of Jiangbei. Cao's army suffered from diseases and many officers died, but the warships remained together. Huang Gai pretended to surrender, burned Red Cliff, and defeated Cao's army. Cao Cao returned from Huarong Road North. Of course, Zhou Yu, one of the heroes of the Battle of Chibi, was not well known. The other is his friend and enemy Zhuge Liang, whom he both loves and hates. The story of Zhuge Liang is familiar to readers. Luo Guanzhong used a large number of artistic methods in "The Romance of the Three Kingdoms", which surprised readers with Zhuge Liang's wind and rain and calculation ability. On the eve of the Battle of Chibi, Zhou Yu prepared to launch a fire attack to burn Cao Cao's warships and defeat Cao Cao. But Zhou Yu made a mistake in his hurry. He did not expect that this fire would require very high wind direction. In winter, the northwest wind is stronger than the southeast wind in the middle reaches of the Yangtze River. If the northwest wind sets fire, and Cao Jun is at the highest point, he will only burn himself, but he will not be able to burn Cao Jun at all.

Zhou Yu could not think of a way. He suddenly became ill. At that time, Zhuge Liang helped Zhou Yu make plans. He knew the cause of Zhou Yu's illness, so he gave Zhou Yu a prescription: "If you want to defeat Cao's army, you must attack with fire.". Everything is ready, just the east wind. Zhou Yu asked Zhuge Liang to find a way to "create" the east wind. Zhuge Liang immediately agreed: "You can borrow it." "So Zhou Yu asked people to build a seven-star altar. Zhuge Liang pretended to go up to the altar and took advantage of the east wind. On the day of the battle, there was a strong southeast wind. Zhou Yu took the opportunity to attack Cao's army.

In fact, Zhuge Liang was good at predicting the weather. He knew from the weather forecast that there would be a southeasterly wind. He was not borrowed at all. How did Zhuge Liang know that the southeasterly wind would blow during the Battle of Chibi? Chibi was located in the middle reaches of the Yangtze River in East Asia. In winter, the land temperature drops faster than the ocean, so cold high pressures often form in Central Asia, such as the Siberian High. As a result, northwest winds should prevail in the Chibi region.