Experimental results on the unsteady behaviour of the wake of a modelled wind turbine in an atmospheric boundary layer (ABL) wind tunnel are presented. Tests were performed by modelling in the wind tunnel an ABL above a neutral moderately rough terrain at a geometric scale of 1:400, and a wind turbine with the help of the actuator disk concept. In order to characterise the meandering properties of its wake, velocity spectra and space-time correlations were measured through hot wire anemometry, both in the wake of the modelled wind turbine and in the wake of a solid disk. Comparing these two configurations allowed the examination of the differences between the random motion of the whole wind turbine wake characterising the meandering in the first case, and the periodic oscillations of the well-known vortex shedding, which appears behind a bluff-body, in the second case. Finally, the same experiments were performed in homogeneous and isotropic turbulent flows to exhibit the role of the large atmospheric turbulent scales in the meandering process.