Earth's rotation causes the trade winds, in a way. If Earth didn't rotate, the wind at these latitudes would blow straight from the subtropical highs to the ITCZ.n the Northern Hemisphere, the Earth rotates counterclockwise so the wind is deflected to the right. The Southern Hemisphere rotates clockwise deflecting the wind to the left. Regardless, the Coriolis effect only influences the direction of the wind, not its speed.