Click the glass to seed a new crystal
This 2D simulator recreates the frost lace that forms on a cold windowpane on a winter night: click anywhere on the glass to plant a nucleation point, and watch six-fold symmetric dendritic ice crystals spread outward as water vapor diffuses in and freezes onto the growing tips. Lower the temperature to push the crystals toward fine, feathery side-branching, or raise the humidity to feed the tips more vapor and speed up the whole pane's coverage, while the live readout tracks how much of the window has frosted over.