NASA does not classify Earth's atmosphere based on chemical composition. The primary classification system for the atmosphere is based on temperature variations, resulting in the following five layers:

1. Troposphere: The lowest layer, where we live, characterized by temperature decreasing with increasing altitude.

2. Stratosphere: Known for containing the ozone layer, where temperature increases with altitude due to the absorption of ultraviolet radiation.

3. Mesosphere: The layer where temperature sharply decreases with increasing altitude, hosting phenomena like noctilucent clouds.

4. Thermosphere: The hottest layer, where temperature significantly increases with altitude due to interactions with solar radiation and auroras.

5. Exosphere: The outermost layer, where the atmosphere merges with outer space.