n. An elliptical fire burning in a uniform fire environment.
Most fires start at an ignition point and spread, initially, in a roughly elliptical shape. The behavior of different parts of such a fire can be predicted from the mathematical properties of an ellipse. Once a fire has spread into a different fire environment – or if the fire environment has changed temporally – it can no longer be considered point-source. In such cases, fire modeling is accomplished by treating the fire perimeter as a series of point-source fires, each in its own uniform fire environment.