This paper presents some results of the lidar investigations into the altitude structure of aerosol fields based on the array of data obtained during the shipborne research mission on Lake Baikal in July-August of 2002. By analyzing the aerosol field cross sections we have revealed a significant effect of local orography on the formation of the field structure. Besides, local features in the spatial aerosol distribution were determined and frequency characteristics of the lee waves were estimated. It was shown that the effect of a mountain ridge on the formation of aerosol field is most pronounced in the central part of the lake with higher mountains on its banks. Here we observed wave motions of two scales along the entire ship route. In the southern part of the lake, small-scale perturbations that are formed behind the ridge spread only up to the central part of the lake. The characteristic feature of the low-frequency atmospheric oscillations is that a linear frequency trend (increase of the oscillation frequency in the direction from the west to the east) occurs.