Wind Turbine Visibility and Visual Impact Threshold Distances in ...

Figure 9. Average visibility ratings by wind turbine/backdrop contrast level (low,
medium, or high) as a function of distance for the Cedar Creek wind energy facility.
Effect of Wind Turbine Lighting Angle on Facility Visibility
A key factor contributing to contrast between the turbines and their visual backdrop is the
relationship of the sun angle and the viewing angle, i.e. whether the turbines are frontlit with
respect to the viewer, backlit with respect to the viewer, sidelit, or unlit (shaded). The
University of Newcastle (2002) suggested that frontlighting and backlighting increase contrast
of wind facilities (depending on the lightness of the backdrop), while shading tends to decrease
contrast.
In this study, as noted in the methodology discussion, the wind turbine lighting angle was a
calculated value and not an observer judgment. A graph of the relationship between wind
turbine lighting angle and visibility rating as a function of distance for the Cedar Creek facility
is shown in Figure 10.
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