What gases are no longer traceable about 19 km up why?

Answer 1

At approximately 19 km above the Earth's surface, in the stratosphere, gases such as methane and carbon dioxide become less traceable due to their mixing and dilution in the atmospheric layers. This altitude is significant as it marks the transition into regions where atmospheric circulation and chemical reactions diminish their concentration. Additionally, the increased temperature and reduced pressure at this altitude can lead to the breakdown of certain trace gases, further complicating their detection. Consequently, the dynamics of stratospheric chemistry limit the presence and traceability of these gases.