Decline in the thickness of ozone layer over a restricted area is called ozone hole. It was first discovered over Antarctica. Antarctica air is completely isolated from the rest of the world by natural circulation of wind called as Polar Vertex.
CFCs released in the atmosphere slowly enters the stratosphere and wind push them towards the poles. Environmental conditions prevailing in Antarctica during winter months are conductive for the formation of ozone hole.
During winter months, lack of sunlight and low temperature facilitates the formation of ice clouds, which provide the catalytic surface for the reaction of chlorine.
Effect of Ultraviolet Rays
1. UV-B radiations are very harmful. Coronea of eye absorbs these radiations and becomes inflamed. This disorder is known as ‘snow blindness’ cataract and leads to diminishing of eye sight.
2. UV-B radiations damage skin cells and cause skin cancer.
