3 ms·

For those skeptical of the science, note that there are large caves that exhibit this property, such as: https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_

For those skeptical of the science, note that there are large caves that exhibit this property, such as: https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#Wind https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#... It seems like if the inside of the chimney column had a spiral shape, similar to a screw socket, the upward air pressure might alleviate some of the stress and make the column more structurally feasible. Granted, it would also dissipate some of the energy as heat.

fenomas 9y ago
Caves like that presumably connect two areas of air that are not otherwise connected, and not in equilibrium with each other, no? Unless I'm missing something, TFA suggests that you can take a big system that's generally in equilibrium, and run a tube from one part to another, and get a similar effect. This seems like a very different proposition from what's happening in caves like you mention.
- koverstreet 9y ago
  The atmosphere is emphatically _not_ in equilibrium. Why would you think it was? There's a giant fusion engine pumping energy into it, resulting in a fuck of a lot of activity (wind). In particular, the upper atmosphere would not be colder than the lower if it was at equilibrium. Think about it.
  - fenomas 9y ago
    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.

fenomas 9y ago

Caves like that presumably connect two areas of air that are not otherwise connected, and not in equilibrium with each other, no? Unless I'm missing something, TFA suggests that you can take a big system that's generally in equilibrium, and run a tube from one part to another, and get a similar effect. This seems like a very different proposition from what's happening in caves like you mention.

koverstreet 9y ago
The atmosphere is emphatically _not_ in equilibrium. Why would you think it was? There's a giant fusion engine pumping energy into it, resulting in a fuck of a lot of activity (wind). In particular, the upper atmosphere would not be colder than the lower if it was at equilibrium. Think about it.
- fenomas 9y ago
  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.