Canagnus effect take place if windspeed is 0 ? Lets assume that our frame of reference a place an earth (e.g. soccer pitch) .We measure the windspeed and we find it zero.But if we make a knuckleshoot then how is it explained ? What produces the pressure difference in order for ball to change direcrion?
The ball moves through the air, which results in a flow around the ball. From the viewpoint of the ball, that's a wind.