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All of the same gases as the troposphere except for a low value of water vapor (mostly because its so cold at the interface). There is also a very small (but very important) amount of ozone and monoatomic oxygen.
The two most abundant gases in any layer of the atmosphere are nitrogen and oxygen. In the stratosphere, ozone composition increases from 0.04 parts per million in other layers to 5-12 ppm. However,...