The atmosphere of the Earth is divided into five layers. From the closest and thickest to farthest and thinnest layer: Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.
The ozone layer refers to a region of Earth’s stratosphere that absorbs most of the Sun’s UV radiation. It was discovered by the French physicists Charles Fabry and Henri Buisson in 1913. The ozone can be measured in Dobson unit (DU) by using a simple spectrophotometer (the Dobsonmeter). It could be used to measure stratospheric ozone from the ground that was developed by the British meteorologist G. M. B. Dobson who explored the ozone properties.
Ozone is an allotropic form of oxygen which contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although it is still very small relative to other gases in the stratosphere. It is a highly reactive gas which reduces the amount of harmful UV radiation from reaching the Earth’s surface.
Resources:
Caroline Tran, Dan Chong , Anne Keith, Jordan Shively (n.d.) ‘Depletion of the Ozone Layer’ Retrieved on 15 March, 2015 from http://chemwiki.ucdavis.edu/Physical_Chemistry/Kinetics/Case_Studies%3A_Kinetics/Depletion_of_the_Ozone_Layer
Freddy (n.d.) ‘Layers of the atmosphere’ Retrieved on 15 March, 2015 from http://clccharter.org/freddy1/weather/atmosphere/layers.html
Unknown (n.d.) ‘Ozone layer’ Retrieved on 15 March, 2015 from http://en.wikipedia.org/wiki/Ozone_layer
Unknown (2010) ‘ The Ozone Layer’ Retrieved on 15th February, 2015 from http://eschooltoday.com/ozone-depletion/where-is-the-ozone-layer.html