Planetary boundary layer refers to the layer of the Earth's atmosphere closest to the surface, where the effects of friction and other factors are significant. Other synonyms for this term include atmospheric boundary layer, mixing layer, and convective boundary layer. The atmospheric boundary layer is where most of the weather we experience occurs, and it is an important area for understanding atmospheric processes. The mixing layer describes the area where warm air rises and cool air sinks, causing turbulence and the mixing of pollutants. The convective boundary layer is where convective currents are most active, and it is an important feature in understanding the dynamics of atmospheric convection.