We seek to gain insight into what these processes are, and their relative importance, using global output at high temporal resolution from the Met Office numerical weather prediction model. We begin by presenting dominant patterns of diurnal variability in EOR, extracted via a principle component analysis. Next, we discuss the physical controls on these dominant patterns, such as surface heating, convective cloud development and marine stratocumulus cloud dissipation. Crucially, this will include examining the extent of coupling between the dominant EOR patterns and the diurnal variability in other relevant geophysical variables. Finally, we point out the significance of diurnal time lags that exist between EOR and the other relevant variables. The robustness of these results is assessed using geostationary satellite observations throughout.