whatA window in the rain. Condensation seeds micro-droplets; droplets grow, touch, and coalesce; pinning holds each one to the glass until it is too heavy to hold. Then it runs -- sweeping every drop in its path into itself, leaving a clean lane that slowly mists over again.

whyThe claim is the rhythm every window-watcher knows: stick... stick... merge -> run. Nothing happens, nothing happens, then everything at once. It is measured: the ledger records what launched every run -- most are launched by a MERGE that vaults a drop past the pinning threshold, not by slow growth -- and the intervals between runs are over-dispersed -- their coefficient of variation holds above 1 (a Poisson rain would sit at 1): clustered, avalanche-like, intermittency you can watch forever. The burstiness index B flickers with the era; the cv does not. Tilt the pane and the pinning threshold falls; click to land a fat drop and start trouble yourself.

howVolume-true coalescence (radii add as cubes) with the survivor remembering it was made by a merge; a drop runs when its radius crosses K over the square root of the sine of the tilt; runners accelerate under gravity with drag, wobble, absorb what they touch, and shed tiny residue beads behind them. Fixed-step simulation, everything seeded; the streaks fade over nine seconds while condensation refills the lanes.