Definition of a "Fireball"

The atmospheric burning of a fuel-air in which the energy is mostly emitted in the form of radiant heat. The inner core of the fuel release consists of almost pure fuel whereas the outer layer in which ignition first occurs is a flammable fuel-air mixture. As buoyancy forces of the hot gases begin to dominate, the burning cloud rises and becomes more spherical in shape.

Fieballs occur with gases and can also occur with liquids where the liquid has been sprayed into the air, such as in an aircraft crash or a BLEVE or where an explosion has taken place inside the liquid.