On completion of this module, you should be able to understand how the location of the ozone layer protects the earth, understand the benefits of the ozone layer. Understand what factors cause the depletion of ozone and understand what measures can affect ozone depletion. The earth’s atmosphere consists of five Layers: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. The stratosphere is the second layer away from the earth’s surface. It is above the troposphere and below the mesosphere. Military planes often fly within the stratosphere which extends from 10 kilometers to 50 kilometers above the Earth. Most commercial airplanes fly under or within the lower part of the stratosphere.