What do you mean by ozone hole? What are its consequences?

Explanation

In Polar regions, stratospheric clouds provide the surface for chlorine nitrate and hypochlorous acid, which react further to give molecular chlorine. Molecular chlorine and HOCl are photlysed to givr chlorine- free radicals.
`ClONO_(2(g)) +H_(2)O_((g)) rarr HOCl_((g))+HNO_(3(g))`
`ClONO_(2(g))+HCl _((g)) rarr Cl_(2((g))+HNO_(3(g))`
` HOCl_((g)) overset(hv) rarr overset(.)OH_((g))+ overset(.)Cl_((g))`
`Cl_(2(g)) overset(hv) rarr overset(.)Cl_((g))+ overset(.)Cl_((g))`
The chlorine-free radicals lead to the decomposition of ozone as :
`overset(.) Cl_((g))+O_(3(g)) rarr Cloverset(.)O_((g))+O_(2(g))`
Hence, a chain reaction is initiated. The chlorine-free radical is continuously regenerated, thereby depleting the ozone layer. This phenomenon is known as the as 'ozone hole'.
Effects of depletion of ozone layer
The ozone layer protects the Earth from the harmful UV radiations of the sun. With the depletion of the layer, more radiation will enter the Earth's atmosphere. UV radiations are harmful because they lead to the ageing of skin, cataract, skin cancer, and sunburns. They cause death of many phytoplanktons, which leads to a decrease of fish productivity. Excess exposure may even cause mutation in plants.
Increase in UV radiations, decrease the moisture content of the soil and damages both plants and fibres.