The air flow near Earth surface might be observed by both qualitative and quantitative methods. Quantitative measurements are extremely important for structural design, giving fit information regarding wind stress or speed, and also about the amount of snow in turbulent diffusion. Nevertheless, we still find an interest concerning the qualitative methods, especially for the wind streams very close to the Earth surface. This approach is quite important for the road designers, because quite often is very difficult to find the right alignment without any prior study in wind tunnel, in order to avoid problems that often occurs in winter for certain road sections. At the Faculty of Civil Engineering of Iasi one realized some tests of smog simulation of the air streams for roads. The goal was to make appears the self-cleaning streams , that usually occurs in the case of deep cuttings, streams that avoid the snowing up of such a cross section by a continuous circular move of the snow. Rigid models have been done, for cut deep from 3 to 10 meters, at a scale of 1/100. The value of scale has been chosen in order to make possible comparisons with similar tests performed in wind tunnels using glass beads. In order to perform the tests, a smog generator using paraffin was created. Pictures in dark have been also taken for every model.