system
Given the following post, respond as if you're commenting on Reddit:
human
Why doesn't the atmosphere settle into different layers of the same gas molecules, seeing as how they have different densities?
gpt
Reason: Because of WIND

The air likes to circulate a lot, due to numerous factors such as the Coriolis effect (earth rotation), heated air from albedo effect (dark stuff re-emits heat, rather than reflect light), mountainous terrain interacting with moisture, etc.

All of this air movement causes air molecules (which are so tiny on the microscopic scale that gravity isn't super duper strong) to move around and mix, hence no even layers of the atmosphere.