The experimental results of the influence of different net structures on the dynamics of wall-free non-stationary air vortices are presented. These vortices were produced over underlying surface of aluminum sheet due to its controlled heating from below as a result of development of unstable stratification of air. It is strictly emphasized that on the contrary to previous studies no mechanical swirling devices and/or underlying surface rotation were used for the vortices generation. We have conducted the experiments on establishing how vertical nets placed in the travel line of a sufficiently non-stationary laboratory vortex affect its dynamics. Six different patterns of behavior of vortices in the interaction with net obstacles were revealed as a result of conducted experiments. We have distinguished several fundamental mechanisms of how nets affect a non-stationary vortex. Among these mechanisms is the action of small-scale turbulence generated behind the net with large-scale turbulence of the model vortex, leading to violation of its symmetry. The generalization is performed of the data obtained concerning the influence of net structures of various geometries on the laboratory-simulated vortices of different intensities. (C) 2013 Elsevier Ltd. All rights reserved.