Solar volcano
Eight-sided translucent teepee · dry floating collector · lagoon fit and reference cases
Seams and ties show geometry; structural support remains unresolved.
Steady, calm-wind screening estimate. Surface temperatures, heat-transfer coefficients, intake and summit sizes are assumptions. Cross-sectional mixing, actual weather and membrane deformation need separate analysis.
The dimensions and loads
| Uniform wind | Pressure scale | Horizontal force scale | Base moment scale |
|---|
These are load scales using air density 1.15 kg/m³ and an assumed drag coefficient of 1.0, not design wind loads. The 60 m/s case is a storm sensitivity case, not a site-specific code wind speed. No foundation, cable, pole or fabric system has been sized.
Where the heat enters
The dry skirt adds no water vapor. Sunlight transmitted through the tall fabric heats the black floor; that energy is counted there once. Only the assumed absorbed fraction of sunlight heats the skin itself. The skin also exchanges heat with outdoor air. The model includes expansion cooling, condensation heat release, droplet loading and outlet acceleration.
After the opening
For the 700 m-radius Clipperton fit, the middle entrainment assumption (0.10) gives about 0.55 km of further rise beneath the test inversion and 0.75 km in the stable test atmosphere: about 2.35 and 2.55 km total altitude. These use the favorable Clipperton outlet and the same illustrative environments described below, not local soundings.
For the original 1 km-radius reference, from its 1.8 km rim, a moist entraining-plume calculation gives another 0.49–0.86 km under an illustrative warm inversion, or 0.65–1.22 km through a steadily stable atmosphere. At the middle mixing assumption, the plume slows to 0.2 m/s at 0.58 km and 0.83 km above the rim, respectively. These are maximum-rise proxies; spreading begins lower, near neutral buoyancy.
The inversion adds 4 K over a 300 m layer beginning 200 m above the rim, with humidity falling from 80% to 40%. The stable case cools by 3 K/km above the rim. All cases start with the same baseline outlet, to isolate the atmosphere above it. With an uncapped 6.5 K/km, 80%-humidity atmosphere, the model permits several kilometres of further ascent; that deep branch omits ice, rainfall and cloud-radiation feedback, so it is not a forecast. Crosswind would bend and dilute the plume. A local sounding is needed to estimate a particular day.
Mixing uses an assumed entrainment coefficient of 0.05–0.15 and follows conservation of moist energy, water and vertical momentum, extending Morton, Taylor and Turner’s integral plume approach.
Basis
Tokyo: Minamitorishima’s land area and elevation · JMA: meteorological observatory · Schlaich et al.: solar updraft towers · Unidata: moist parcel thermodynamics · NASA: wind-force scaling