2D Snowfall: Terminal Velocity, Wind Drift & Accumulation

This is the 2D companion to the 3D snowfall scene: a side-on canvas view built around the physics that decorative snow animations usually skip. Each flake carries its own size, and drag versus gravity gives it a real terminal velocity — bigger, denser flakes outrun smaller ones on the way down. Wind adds a controllable horizontal drift, and temperature reshapes the snow itself, from small dry powder that piles up deep and fluffy to large wet flakes that pack down into a shallower, denser layer, with live readouts for ground depth, flake count, and average fall speed.