The atmospheric boundary layer over mountains shows a wide range of special characteristics, especially when mountains are covered with snow. This contribution discusses how cloud dynamics, prferential deposition and snow transport shape the obeserved high variability in alpine snow distributions. With respect to spatially varying snow melt, we ufrther show how boundary layer on one side and topography with or without snow interact. A partially snow-covered landscape is used to demonstrate the effects. The processes diecussed have implications for the atmosphere but also for hydrology, vegetation and avalanche formation.