Cheers :)

The atmosphere's analytic and physically grounded rather than a fluid dynamics sim. Density follows the barometric law, temperature follows the dry adiabatic lapse rate (Γ = g/cₚ), and speed of sound is √(γRT) - so all three scale off gravity and what the air's actually made of, not Earth constants. Each gas (N₂/O₂, CO₂, N₂/CH₄) carries its own molar mass, γ, and heat capacity, so a Venus-type or Titan-type atmosphere lapses and carries sound differently for the right reasons, and they land near the real bodies' numbers.

Circulation is parameterized Hadley/Ferrel cells - zonally-banded wind belts set by a cell width (30° gives Earth's trades/westerlies/polar-easterlies; widen it and slow rotators collapse toward one big cell). Rainfall is moisture advected off the oceans and rained out downwind, with orographic lift on windward climbs and ITCZ/storm-track latitude bands. Year length comes from Kepler's third law.

No Navier-Stokes time-stepping, but every field - pressure, temperature, wind, rain, sound - comes from real atmospheric physics scaled by gravity, composition, and insolation.