A fuel-bed cellular automaton with Rothermel-style spread. Set wind, fuel moisture, fuel load and slope, then click the terrain to ignite. Watch the fire front, smoke column, ember spotting and the live rate-of-spread, flame length and fireline intensity.
Spread uses a simplified Rothermel-style rate: R = R₀·exp(0.09·w)·exp(−0.09·fm)·(1+0.05·slope), wind direction weighted by cos(Δθ) so the head fire runs downwind. Flame length from Byram’s line fire intensity: I = H·w·R (H = 18 MJ/kg), L = 0.0775·I^0.46 m. Spotting embers jump ahead in strong wind; moisture above ~25% essentially stops spread, as it does in real fuel beds.