Question

use the information about CFCs to explain by the hole in the Ozone Layer appear in The Antarctic spring not in the Antarctic winter.​

Answer 1

The ozone hole has developed because people have polluted the atmosphere with chemicals containing chlorine and bromine. The primary chemicals involved are chlorofluorocarbons (CFCs for short), halons, and carbon tetrachloride. CFCs in particular have been used for a wide range of applications, including refrigeration, air conditioning, foam packaging, and making aerosol spray cans. Because these chemicals are so inert, they are able to stay in the atmosphere long enough to be carried upwards to the stratosphere where they can damage the ozone layer.

The actual processes by which CFCs (and other ozone depleting chemicals) destroy ozone are complex and require certain weather conditions to exist. A simplified description of the process involving CFCs is as follows:

Once they reach the stratosphere, un-reactive CFCs can be broken down by UV radiation to release reactive chlorine

For this to occur, clouds need to be present in the stratosphere to provide ice crystal surfaces on which these chemical reactions can take place

Once released from CFCs, chlorine (Cl) then reacts with ozone (O3) to form ClO and O2

ClO quickly breaks down to release the Cl atom which can repeat the process with another O3 molecule

In this way, one chlorine can gobble its way through around 100 000 molecules of ozone before it leaves the stratosphere

The fact that most of the ozone depletion happens over Antarctica also requires some explanation. CFCs and other ozone depleting gases may come from anywhere, but it is in the south polar stratosphere where the conditions become most favourable for ozone destruction. The key factor is the presence of stratospheric clouds and the lack of atmospheric mixing between the south polar latitudes and air from elsewhere during the austral winter and early spring.