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Primary Chemical Components
The stratosphere, and the overall atmosphere, is comprised of three primary chemicals. The most prevalent chemical is nitrogen, accounting for 78 percent of the atmosphere. Oxygen is the second most abundant chemical in the stratosphere, representing 21 percent. Argon is the final primary component of the stratosphere, accounting for 1 percent.
Stratospheric Ozone
Ozone, made up of three oxygen atoms bonded together, comprises less than 0.01 percent of the stratosphere; however, 85 to 90 percent of all the atmosphere's ozone is found there. Ozone is the primary reason the stratosphere is so stable. As ozone molecules absorb dangerous UV radiation, they warm. This results in an inverse temperature gradient in the stratosphere, leading to vertical stability. A naturally occurring, steady-state concentration of ozone exists, meaning it is naturally created as quickly as it is naturally destroyed. However, other chemicals, such as chlorofluorocarbons, can increase the rate of ozone depletion, exceeding nature's ability to create it.
Chemical Components with Long Life Spans
Because the stratosphere is so vertically stable, it takes a long time for chemicals to rise through it, or filter out of it. Several chemicals, which survive for long periods of time, are found in this atmospheric layer. These chemicals include carbon dioxide, nitrous oxide and methane. These chemicals are considered greenhouse gases, meaning they trap heat beneath the stratosphere. Carbon dioxide, nitrous oxide and methane gases are naturally occurring; however, they are also created in industrial processes. Another group of chemicals with long life spans are chlorofluorocarbons. CFCs do not occur naturally and have been shown to play a role in ozone depletion.
Volcanic Chemical Components
While it takes a long time for chemicals to work their way into the stratosphere, volcanic eruptions can rapidly inject large amounts of chemicals into this layer. When this occurs, these chemicals remain in the stratosphere for extended periods of time as they slowly precipitate out. While there, these chemicals absorb solar radiation, producing a rise in stratospheric temperatures and a drop in tropospheric and surface temperatures. The resulting climate changes can last as long as one to two years. A primary example of these materials is sulfur compounds, such as sulfur dioxide. As sulfur dioxide slowly filters out of the stratosphere, it also mixes with water vapor in the troposphere to produce acid rain. Other volcanic materials include nitrates, silicates, halide salts, heavy metals and soot.