Rayleigh–Bénard convection — Shimizu–Morioka large-Rayleigh-number truncation (Shimizu & Morioka 1980) — dx/dt = y, dy/dt = x − λy − xz, dz/dt = −αz + x². Classic α=0.375 λ=0.81. Dual α+λ sliders. Lorenz-like butterfly for large Ra, distinct ODE from Lorenz-1963 (σ(y−x), x(ρ−z)−y, xy−βz). Bulk centroid ≈ (−0.003, −0.001, 0.938) from warm 20k + 80k RK4 @ dt=0.01. Distinct from Hadley (Lorenz 1984), Lorenz-84 four-slider, Lorenz butterfly, Dequan–Li, Coullet, Burke–Shaw, Sprott–Linz A–S, Finance, Bouali, Genesio–Tesi, Arnéodo, Newton–Leipnik, Rabinovich–Fabrikant, Nosé–Hoover, Rucklidge, Wang–Sun, Lü, Chen, four-wing Qi, Dadras, Halvorsen, Chua, Aizawa, Thomas, Rössler, Newton basins. RK4, not lorenz.html, not hadley.html, not lorenz84.html. Gold low-alpha trail, cap 650. RM = settled silhouette, no animate-on.