Ozone in high concentrations is a poisonous pale blue gas. In small concentrations it has a pungent odor. It is produced naturally by electric discharges, by lightning, and high voltage electrical equipment. Near the ground level it forms a part of the photochemical smog and is produced by chemical reactions involving sunlight acting on pollution.
Ozone can be a beneficial compound when used in the chemical industry as a bleaching agent and a strong germicide to both sterilize drinking water and swimming pools. From a distance, ozone is essential to our well-being. In the stratosphere the ozone protects the surface of the Earth from ultraviolet radiation produced by the sun. Ozone is different from oxygen and is essential for all forms of life on Earth. Molecules of oxygen contain two oxygen atoms while molecules of ozone contain three oxygen atoms. The difference between the two is life and death for any animal that breathes in more than a trace of ozone.
The atmosphere of the Earth serves as a warm blanket of oxygen suitable for the life forms that have evolved under it. The hole in the sky over Antarctica generated great concern that the atmosphere may now be changing, triggering conditions never experienced before.
The atmosphere is divided into layers which are described in terms of the way temperature changes with altitude.
The layer of atmosphere closest to the earth is the troposphere: It is the part that we breath and in which our weather occurs driven by convection. The troposphere is relatively thin due to the weight of the air above it. The troposphere is the densest part of the atmosphere containing 85 percent of the atmosphere’s mass. The remaining 15 percent is virtually in the stratosphere which contains air mass below 25 miles altitude. The air in the stratosphere is thin. The stratosphere also absorbs heat from the sun in the form of ultraviolet radiation (UV), because the oxygen seeping up from the troposphere absorbs energy from the sun. Chemically, solar radiation breaks apart the 2 atoms of oxygen in a molecule of diatomic oxygen, and forming two molecules of ozone as a result. The term ozone layer is synonymous with stratosphere. The stratosphere is warmer at higher altitudes. Therefore, hot air does not rise since the air above is hotter than the air below. Hence, convection cannot occur. Since the stratosphere acts like a lid on the troposphere, it keeps convection and weather below the tropopause.
Ozone Layer Today
The ozone layer exists because of the production of oxygen by living things in the troposphere seeping up into the stratosphere and reacting with sunlight forming triatomic molecules of ozone. The presence of so much free oxygen today explains how the ozone is maintained.
The validity of the explanation depends on both the nature of the radiation of the sun and the manner in which ozone and oxygen respond to that radiation. The sun emits energy mostly in the form of yellow light which has a wavelength range of 500 to 600 nanometers (nm). To our eyes the visible light appears red at 76 nm to violet at 400 nm. Nevertheless, there is still a significant amount of solar energy radiated from the sides of the band in the infrared and the ultraviolet.
Specific wavelengths of radiation affect all molecules and a certain amount of energy is needed to break the connection of any particular molecular bond.
In the stratosphere ozone is constantly being produced and destroyed by interactions involving sunlight and oxygen.