As altitude increases, more ultra-violet radiation is present in the Earth’s atmosphere as it can only penetrate so far down before the atmosphere thickens and it is absorbed or reflected.
CFC’s such as H2CFCH2Cl are inert gaseous molecules in the troposphere. However, as the molecules rise up to the stratosphere, the carbon-halogen bonds break homolytically because the uv radiation causes them to photodissociate. This will set off a radical chain reaction, until most of the molecule has turned into something else.
|