Antarctic ozone hole

(meteorology) In the spring, the depletion of stratospheric ozone over the Antarctic region, typically south of 55° latitude, the formation of the hole is explained by the activation of chlorine and the catalytic destruction of O₃, it occurs during September, when the polar regions are sunlit but the air is still cold and isolated from midlatitude air by a strong polar vortex. Also known as ozone hole.