4.12

4.12 Recall that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases

a) UV light / sunlight: short waves and high energy

b) 50% of the light is reflected back out into the space

The main cause is the clouds.

c) Absorption on the earth’s surface. The UV light is converted

into infrared.

d) Infrared light (longer wave)

e) Some being emitted back outwards.

Some of this is lost to space as heat.

f) The greenhouse gases hit by infrared à absorb energy

à re-emits in all directions including downwards

à raises surface temperature

Enhanced greenhouse effect

If we raised the levels of gluten gases like carbon dioxide and methane, they will absorb more of the escaping infrared radiation and re-emit them back to the earth à high temperature à climate change

CFCs chlorofluorocarbons:

CCl₃F broken down by sunlight à CCl₂F^- + Cl^-

They affect the ozone layer (O₃) by catalysing them to break down into O₂. This is very different to chlorine gas. O₃ is better at absorbing UV light. We are removing the protection of ozone layer.