Why is there fog when Zhuge Liang borrows an arrow?

Historical background: The story of a straw boat borrowing an arrow happened in the late Eastern Han Dynasty. Cao Cao, Liu Bei and Sun Quan have their own sides. At that time, Cao Cao had just defeated Liu Bei and sent troops to attack Sun Quan, so Liu Bei and Sun Quan joined forces to resist Cao Cao. Liu Bei sent Zhuge Liang to Sun Quan for help in the war. The story of Zhuge Liang borrowing an arrow from a straw boat happened when Sun Quan and Liu Bei jointly resisted Cao.

1. Zhuge Liang borrowed more than 100 thousand arrows from Cao Cao out of thin air. The main reason is fog. Without fog, he has no chance of success. Once Cao Bing found out the situation, the 100,000 arrows were destroyed.

Of course, strong wind is also essential. If there were no wind, Cao Jun's army would attack, and it would be useless for Wu Dongren to see water again. Another, Cao Cao is too suspicious. He thought that the enemy had really attacked and lost 100,000 arrows. Even if a ship is sent for reconnaissance, it will not suffer this loss. Tens of thousands of arrows were shot, and ordinary people were shot dead. Will he shoot again?

3, to have preventive measures, he will inevitably think of borrowing arrows. Besides, who will have an attack in foggy days? I can't see anything clearly when I fight, so I can only kill each other.