Wind turbines have consistently grown larger and taller over the past decades, interacting with ever larger portions of the highly turbulent lower atmosphere. The Department of Energy (DOE) has stated the goal to produce 20% of the nation’s electricity from wind by 2030. To achieve this goal, major reductions in cost of energy for wind energy are required through improvements in wind turbine reliability together with increased wind farm power capture. The DOE ‘Cyber Wind Facility’ at Penn State was designed to be an ‘experimental’ facility using petascale high performance computer systems that closely mimics a utility-scale wind turbine test facility in the field. In this seminar I will present our research on the interactions between the passage of daytime atmospheric turbulence structures through wind turbine rotors and the consequent non-steady wind turbine load transients. Using large-eddy simulation (LES) of the atmospheric boundary layer (ABL), we have shown that the energy containing eddies in the daytime ABL are of the order the blade length in size and pass through the wind turbine rotor plane over multiple rotation time scales of commercial wind turbines. Using a simulation of a single rotating blade from the NREL 5-MW wind turbine operating in a daytime ABL in which we resolve both the atmospheric eddies and the blade boundary layers using hybrid URANS-LES, we segregate the non-steady load changes on the blade into 3 distinct time scales: sub blade-rotation time scale, near blade rotation time scale, and eddy convection time scale. We find that eddy-induced non-steady changes in the velocity angle dominate the load fluctuation dynamics at all time scales.