A flame ball growing into a turbulent mixture exhibits a speed which is proportional to its size-this effect is a consequence of the distorted flame surface: the inner flame regions ＇＇push＇＇ the outer regions, the magnitude of this velocity depends upon the flame surface density distribution. A simple two-dimensional, zero-thickness flame model interacting with defined eddies illustrates how rapidly this flame distortion occurs after a spark ignition. This distributed volume source effect is also the functional form of Groffs modified entrainment model of flame propagation. A result of this size dependent growth is exponential growth of flame area which is an essential feature of spark-ignition internal combustion engines.