Polynyas and the overlying atmosphere interact through a series of feedback mechanisms which impart a distinctive polar maritime character to the boundary layer over and downwind of the open water area. Enhanced turbulent fluxes across the ice-free interface introduce heat and moisture into the otherwise cold, dry polar atmosphere, modifying clouds through plume formation and radiative exchanges between the atmosphere and underlying surface. Anthropogenic aerosols of remote origin and local biogenic emissions provide additional direct and indirect radiative forcing, which may also influence precipitation rates, cloud optical depth, and ozone concentration. These combined effects modulate the efficacy of polar regions' ability to act as a "heat sink" for the climate system, establishing a link between the regional polynya meteorology and global conditions. Models, gridded analyses, and remotely-sensed and validating measurements which describe the meteorology and feedback mechanisms in and around polynyas are discussed in this chapter, with an outlook toward future efforts and novel measurement and analytical techniques.