1. For air blowing toward an object such as the wall of a building, the point that marks the center of divergence of air along that wall as the streamlines split to flow around the building. The stagnation area corresponds to a relative maximum of static pressure. 2. During strongly statically stable conditions, the region just upstream of a mountain where the air is blocked by the mountain. This blocked flow could also contain a cavity of reverse flow. 3. An air pollution term for an anticyclonic region of subsidence and light winds that tends to trap pollutants near the ground where concentrations can become large.