Atmosphere Question

[foodchain]

Is there any strong sets of chemical data available on any attempts to experiment or recreate say compositional differences with the existing layers of the atmosphere? I don’t want to look at say the evolution of its various layers just more or less differences with them as they existed in time together.

 

*Physically speaking can you ignore the history of a system? TO what extent in regards to say this question. I just want to ignore I guess the “time-evolution” of the atmosphere to certain bounds in its past, how do I subtract out the history? This question is purely bonus.