[A]
Absence of polar front and stratospheric clouds; and inflow of methane and chlorofluorocarbons.
[B]
Increased temperature at polar region due to global warming.
[C]
Presence of prominent tropo- spheric turbulence; and inflow of chlorofluorocarbons.
[D]
Present of prominent polar front and stratospheric clouds; and inflow of chlorofluorocarbons.