I am trying to understand wind turbine efficiency and the phenomena of Betz's Law. I have a basic grasp of Betz Law which says the maximum efficiency of a wind turbine is 59 % energy capture of the wind swept turbine area (more or less in those words). I understand that when the wind hits the turbine and energy is transferred to the turbine, the air molecules slow down and impeded the incoming air molecules from getting through and slows them down -- which in turn reduces the kinetic energy captured by the turbine blade. Is this the only phenomena that contributes to the 59 percent efficiency dictated by Betz? (I am not talking about friction loss in generator etc.. just kinetic energy capture of the wind sweep area). Isn't there some loss of kinetic energy capture - especially in slow winds caused by the air molecules going straight through the sweep area of the blades without touching the blade and is not captured by the turbine at all?