> The constricted center accelerates the flow upward. And the wider top helps promote mixing of the hot humid air with the cooler air outside. But, really, these are secondary benefits. The main reason for the shape is structural.
> [...] the double curvature of a hyperboloid stiffens the shell against vertical loads like the structure’s own weight and horizontal loads like wind.
> The constricted center accelerates the flow upward. And the wider top helps promote mixing of the hot humid air with the cooler air outside. But, really, these are secondary benefits. The main reason for the shape is structural.
> [...] the double curvature of a hyperboloid stiffens the shell against vertical loads like the structure’s own weight and horizontal loads like wind.