If earth did not rotate, what would happen to the global winds and why?
The global winds would be very light and always in the same direction.
This is my opinion based on what I imagine would logically happen.
The lack of rotation would reduce the Coriolis effect to essentially zero. That means that air would move from high pressure to low pressure with almost no deflection at all. This would mean that high pressure centers and low pressure centers would not form locally.
There would be a permanent high pressure center at the sub point of the sun, and a permanent low pressure on the dark side of the planet due to the relationship between pressure and temperature. Since the pressure would balance out quickly due to no Coriolis, the difference between the high pressure side and low pressure side would be very little. The moving wind would always bring warm air from the "summer" side to the "winter" side and make the temperature difference very small.