I didn't say the system was closed. Why would you think I did? All I meant was that energy is free to flow around the atmosphere if it wants to; any macroscopic flow that wanted to occur would have occurred already.
In other words, caves like the GP mentioned (presumably) connect two systems between which energy is not otherwise free to move. That is not the case for a tube connecting two different sections of the atmosphere. Make sense?
> In particular, the upper atmosphere would not be colder than the lower if it was at equilibrium. Think about it.
Temperature varies inversely with pressure for a volume of gas. If low- and high-atmosphere gas had the same temperature, despite being at different pressures, that would be an imbalance.
In other words, caves like the GP mentioned (presumably) connect two systems between which energy is not otherwise free to move. That is not the case for a tube connecting two different sections of the atmosphere. Make sense?
> In particular, the upper atmosphere would not be colder than the lower if it was at equilibrium. Think about it.
Temperature varies inversely with pressure for a volume of gas. If low- and high-atmosphere gas had the same temperature, despite being at different pressures, that would be an imbalance.