Downward movement of fire occurs when burning embers drop

Downward movement of fire occurs when burning embers drop from an upper area to a lower area especially in balloon-frame construction. Fire can also travel downwards along walls especially if combustible materials such as paint, varnish, or flammable paneling cover these walls. This is usually a slow process and is responsible for minor dissemination of fire. Fire follows a slope on which highly combustible liquid has been poured. An example is when gasoline is poured down a staircase. Initially fire burns n a downward direction following the flowing gasoline, thereafter it starts burning in an upward direction once the gasoline vaporizes