Page 1 - 2. Lesson notes-Ozone layer Depletion

SAI International School
Subject- Biology, Class- X
Chapter- Our Environment
Subtopic- Ozone Layer and its Depletion
Managing the Garbage that We Use
Module-32
Lesson Notes

THE OZONE LAYER

 The ozone layer is a deep layer in the stratosphere, encircling the Earth, that
has large amounts of ozone in it.
 The layer shields the entire Earth from much of the harmful ultraviolet
radiation that comes from the Sun.
 For nearly a billion years, ozone molecules in the atmosphere have protected
life on earth from the effects of ultraviolet rays.

Depletion of ozone layer in the atmosphere

Ozone molecule contains three oxygen atoms (O ). At higher levels in the
3
atmosphere the UV radiation splits some oxygen molecules (O ) into free oxygen
2
atoms which combines with oxygen molecules (O ) to form ozone. It is highly
2
poisonous.
UV radiation
O O + O
2
O + O O
2 3
(Ozone)