The stratosphere is primarily composed of the same elements as the rest of the Earth's atmosphere:

* Nitrogen (N2): Makes up about 78% of the stratosphere.

* Oxygen (O2): Makes up about 21% of the stratosphere.

* Argon (Ar): Makes up about 1% of the stratosphere.

However, the stratosphere has a unique composition compared to the troposphere (the layer below it) due to the presence of ozone (O3):

* Ozone (O3): This is a key component of the stratosphere, forming the ozone layer. It absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth.

While other trace gases like carbon dioxide (CO2) and water vapor (H2O) are present in the stratosphere, their concentrations are much lower than in the troposphere.