THE OZONE HOLE
In 1985 it was discovered that there was a much lower concentration of ozone over Antartica during spring time. During winter, very low temperatures over the South Pole cause the formation of polar stratospheric clouds (PSCs) within a vortex of swirling cold air. The formation of PSCs involves the production of chlorine which in the spring, when sunlight is available, is used to destroy ozone, causing a temporary drop of about 50% of ozone concentration.
An ozone hole only occurs above Antartica because the bulk of land mass at the northern hemisphere disrupts the meteorology there, causing higher temperatures and weaker PSC formation.
Mending the Hole…