Ask A Scientist© Environmental Science Archive

Author:     proclus
Text:       How was the ozone layer created?

Response #: 1 o f 1
Author:     Mark Fernau
Text:       A long time ago, plants began to grow on Earth and they released 
oxygen molecules (02) into the atmosphere, and these oxygen molecules traveled 
to the stratosphere (the part of the atmosphere above where planes fly where 
temperature begins to increase with height again). Ultraviolet radiation from 
the strikes these molecules and splits them into two oxygen atoms (O + O). 
Then the oxygen atoms combine with an oxygen molecule to make ozone (O + 02 -> 
03). Above this layer there are not as many oxygen molecules and below this 
layer the W radiation cannot reach so the ozone is concentrated at the height 
of the layer.