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

 Short wave UV radiation from the sun reaches the earth and some is absorbed and used but should then 

be reflected back out into space as longer wave thermal radiation, however greenhouse gases absorb this

heat that is reflected by earth and the heat is trapped in the atmosphere, causing the warming of earth.

These gases are necessary for keeping our planet warm enough for life but large quantities of these gases

enhances the greenhouse effect and can cause the climate to change and temperatures to rise.

Some of the greenhouse gases are:

-                 Water vapour

-                 Carbon dioxide

-                 Nitrous oxide

-                 Methane

-                 CFCs (chlorofluorocarbons)