OZONE LAYER

To understand Ozone layer, it is important to know the different layers of the atmosphere. The earth's atmospher is composed of many layers, each layer plays a significant role.

The first layer is Troposphere which stretches approximately 10 kilometers upwards from the earth's surface. A lot of human activities such as gas balloons, mountain climbing and small aircraft flights take place within this region.
Another layer is Stratosphere which is the layer of the earth's atmosphere and is above the troposhere stretching approximately 15 to 60 kilometers.
The Ozone layer sits in the lower region of the stratosphere from about 20 to 30 kilometers above the surface of the earth. The thickness of the Ozone layer is about 3 to 5mm, but it always fluctuates depending on the season and geography.

The Ozone layer which is known as Ozone shield is a region of earth's stratosphere that absorbs most of the Sun's Ultraviolet (Uv) radiation. It contains high concentration of of Ozone in relation to other parts of the atmosphere.

                          SOURCES

Ozone in the Earth's stratosphere is created by ultraviolet light strikingordinary oxygen molecules containing two oxygen atoms (O 2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O 2 to create ozone, O 3. The ozone molecule is unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O 2 and an individual atom of oxygen, a continuing process called the ozone-oxygen cycle .
Chemically, this can be described as:
O 2 + uv → 2O
O + O 2 ↔ O 3