Why do tall chimneys provide better circulation?

Question

I'll be grateful for a detailed explanation based on physics.

Answer 1

Warmer gases always will tend to go up, no matter they are located, this has to be the basic principle for chimneys.

If a chimney is short enough, the warm smoke can not be naturally forced, up, it can be at first in a kind of blocked or clogging situation, and eventually can return down.

A well designed chimney has a broader base and a reduced upper exit, in order to create a vacuum effect, that eventually will promote the upper travel of smokes, and a quicker expelling.

Of course there has to be a limit height to any chimney, depending on the smoke composition, the generating temperature, and that of the exterior; also the gravitational force of the area.

Answer 2

I think its because their stack is wider maybe