The cylinder interior has a counterintuitive thermal layout that drives everything: "up" — toward the axis — wants to be hot, not cold. The linear sun is on the axis; the cold sink is the shell radiating to space at the rim. That inverts Earth and produces permanent stratification: warm air rises to the core and stays there, the water cycle goes dew-dominated, not rain-dominated, and the same stagnation that waters the plants starves them of CO₂. tide is the toolkit for that physics.
The O'Neill cylinder model is built as four independent surfaces. tide is the thermodynamics; its siblings model the structure that holds the air in, the ecology the air sustains, and the game played inside.
The sun is on the axis; the cold sink is the shell radiating to space at the rim. That inverts Earth — warm air rises to the core and stays there.
Condensation happens on the cold surface: a cloud-forest of dew and canopy fog. The 8 km build spans ~31 K and ~32% pressure drop, axis to floor.
The cold-surface stratus Mie-scatters the axial sun (a near-blackout at night), while its near-IR fraction is absorbed and evaporates the deck by day.
Stratification suppresses mixing; a canopy depletes its own CO₂ boundary layer. The thermal tide and a mechanical fountain are the pumps that relieve it.
The cylinder is symmetric along and around its axis, so the only gradients are radius and azimuth. Resolve each in turn, then close the books that cross them.
The smallest honest model: give it a radius, a spin, and how much air is inside (its
non-spinning pressure) and it draws the two profiles every other module sits on —
gravity g(r)=ω²r (zero at the axis, full at the rim) and the isothermal
centrifugal barometer P(r)=P_axis·e^{S(r/R)²}. One dimensionless number
S = v²_rim/2c² sets the rim/axis pressure ratio (exactly e^S); the
"non-spinning pressure" can be read as the same air at rest (mass-conserving) or held
on the axis.
A 1-D column model along the radius: temperature, pressure, humidity and CO₂ as functions of altitude and time, under a pulsable axial sun. Where "up is hot" stops being a slogan and becomes a fog-height number — the dew profile, the stratified dead-zone, and whether pulsing the sun ventilates the canopy. Centrifugal hydrostatic balance and the centrifugal adiabat reproduce the geometry's numbers by construction.
The other free dimension — azimuth — looking straight down the axis. A fountain at the rim low point ("Fond du Lac") throws pond water inward; at ~430× Earth's spin the Coriolis force rivals gravity, so the jet curves into a sheet — aerating the water, lofting surface air through the inversion, and laying irrigation down across the hoop, all in one act. The same view carries the luminous-flux budget: the axial sun is a line (irradiance ∝ 1/r), so flooding the 8 km wall takes a ~50 MW-per-metre lamp — with a boiling-sun heat closure that says half a sun is the sweet spot.
Lakes on a spinning floor. In the rotating frame "level" means constant radius — a lake surface is an arc concentric with the axis, never a secant line (a chord would sag ~300 m of spurious head across a 4 km lake), and a smooth cylinder holds no lakes at all, only a film. So the floor is carved into ratchet teeth: a steep scarp prograde of each lake, a long glide descending into the next basin. The Coriolis-drifted jet sheet either drains home or clears the crest and ratchets forward — a river that circulates the rim for ever.
The water and energy books that cross every module — reactors → light + jets (the only loads), and a closed water loop (lake → jet → fog/dew/soil → drainage → lake) that conserves to machine precision. It sizes the reactor (almost all light — the jets are <0.1%), sets the lake depth from the reservoir charge, and turns that water into fish — three corkscrewing lakes that feed the crew's protein several times over. Surfaced in the fountain view alongside the three jets and three lakes.
An odd tenant on this wing: the social climate. The hoop econ society (people who wear many hats across the places) rendered as a web instead of a map — tribes emerge from the tie graph (nothing is assigned), a romance layer sparks over it, and two tension gauges read the weather: tribalism (how little crosses the lines) and the narcissism of small differences (near-twin tribes that barely speak). The drama feed is the proto-oracle.
Goss's sister: procedurally generated murder mysteries read off the civic web. Motive is the native resource (the drama layer supplies suspects and red herrings alike), alibis fall out of each soul's daily watches, and only independent witnesses clear a name — the household swearing to you is worth what kin's word is worth. Every case is certified solvable by a deductive oracle, and every closed case scars the web: victim buried, culprit taken, the next case generated from the survivor society.
The iconic O'Neill view — looking "up" and seeing land curve overhead — but with the atmosphere rendered: the axial sun, the canopy on the inner surface, fog banding by altitude, and a WebGPU slice of the Coriolis-organised convection. Fed by this wing's validated state, so it shows physics, not assumptions.