Pacific lows spin up offshore and ride the jet into the coast; the Cascades wring them dry — watch the rain shadow, the snowpack, the rivers breathing seasonally, fog pooling in valleys at dawn, glaciers creeping over decades. The climate slider warms or cools the whole world: push it cold and ice wins; hot and the forests brown out. Freeze a circle of the Pacific (❄️) and watch the sea slowly erase your mark.

Terrain: NOAA ETOPO1 (public domain). Sim inspired by David A Roberts' “Humanity”, nielsdaemen's 2D Weather Sandbox, and Grant Kot's fluid toys. WebGPU required. Served over http, the whole simulation runs in a worker thread; opened as a file it falls back to the main thread.