  Numerous studies have shown that wind turbine wakes within a large wind farm
bring about changes to both the dynamics and thermodynamics of the atmospheric
boundary layers (ABL). Previously, we investigated the relative humidity budget
within a wind farm via field measurements in the near-wake region and large
eddy simulations (LES). The effect of the compounding wakes within a large wind
farm on the relative humidity was also investigated by LES. In this study, we
investigate how the areas of relative humidity variation, that was observed in
the near-wake, develop downstream in the shadow region of a large wind farm. To
this end, LES of a wind farm consisting of 8x6 wind turbines with periodic
boundary condition in the lateral direction (inferring an infinitely wide farm)
interacting with a stable ABL is carried out. Two wind farm layouts, aligned
and staggered, are considered in the analysis and the results from both
configurations are compared to each other. It is observed that a decrease of
relative humidity underneath the hub height and an increase above the hub
height build up within the wind farm, and are maintained in the downstream of
the farm for long distances. The staggered farm layout is more effective in
keeping a more elongated region of low relative humidity underneath the hub,
when compared to the aligned layout.
