An examination is given of the way in which the saltation layer is affected by the characteristics of the particles. Special attention is given to the potential importance of aerodynamic entrainment during steady state saltation, a topic for which the discussion is still unresolved. A new numerical model for saltation in steady state is presented, which is focused on the computation of the horizontal mass flux. The numerical computations, combined with physical arguments, suggest that aerodynamic entrainment plays a more important role than generally assumed so far. A comparison of the model results is made with previous models, and with measurements of snow saltation that have been reported in the literature.