The Ignition Component is a number which relates the probability that a fire will result if a firebrand is introduced into a fine fuel complex. The ignition component can range from 0 when conditions are cool and damp, to 100 on days when the weather is dry and windy.
Ignition normally takes place in the dead component of the fine fuels.
Three distinct steps must be considered in this ignition process. Living material in the fine fuel complex reduces the efficiency of ignition. The closer the initial temperature of the fuel is to the ignition temperature, the more likely a fire will result when a firebrand in introduced into the fine fuel complex, since not a much energy is required to raise the fuel particle to its ignition temperature. The Spread Component is a numerical value derived from a mathematical model that integrates the effects of wind and slope with fuel bed and fuel particle properties to compute the forward rate of spread at the head of the fire. Output is in units of feet per minute.