Turbulence and wind shears are an example of changing forces that change momentum. Yes, the wind itself doesn't affect the plane. It's the change from one wind speed and/or direction to another that momentarily change the planes airspeed. Doesn't necessarily affect lift and may or may not affect a plane adversely depending on how gradual the change is. A wind shear is a sudden change. A long sweeping turn in a given wind speed is a gradual change. It's just Newton's laws of motion.