East wind in Battle of Red Cliffs, does east wind actually refer to northwest wind or northeast wind?

Kong Ming borrows the east wind-make good use of the weather. This two-part allegorical saying comes from a story in Romance of the Three Kingdoms. The general idea is that on the eve of Battle of Red Cliffs, Zhou Yu is going to launch a fire attack, burn Cao Jun's warships and defeat Cao Cao. However, Zhou Yu made a mistake in his busy schedule. He didn't expect that the fire attack had high requirements for the wind direction, and in the middle reaches of the Yangtze River in the middle of winter, there were many northwest winds and no southeast winds. If you light the northwest wind, Cao Jun is in the limelight, but he just burns himself, and he can't burn Cao Jun at all. Zhou Yu couldn't figure out a way and fell ill at once. Zhuge Liang was in Zhou Yu's army, helping to make plans. After learning the cause of Zhou Yu, he gave Zhou Yu a "prescription": "If you want to break through Cao Jun, you must attack with fire. Everything is ready, only the east wind. " Zhou Yu asked Zhuge Liang to find a way to "engage in" Dongfeng, and Zhuge Liang immediately promised: "You can borrow it." So Zhou Yu had a seven-star altar built, and Zhuge Liang pretended to go to the altar to "borrow the east wind." On the day of the battle, the southeast wind was strong, and Zhou Yu took the opportunity to attack and captured Cao Jun at one stroke. In fact, Zhuge Liang is good at predicting the weather. He knew through the forecast that there was a southeast wind that day, and there was no "borrowing" at all.