Zhuge Liang chose the arrow when the fog was all over the sky. This is for the sake of

The purpose of holding an arrow in foggy days is to confuse the opponent with the east wind, so that the opponent can't see the enemy clearly and dare not play easily; "The bow faces west and the stern faces east" is to make it convenient and fast to return; "Queuing" is to increase the area of arrows and get more arrows; While beating gongs and drums, he shouted, "It is to create momentum so that local governments will not dare to go to war easily without knowing the enemy's situation."