A firestorm is a conflagration which attains such intensity that it creates and sustains its own wind system. It is most commonly a natural phenomenon, created during some of the largest bushfires and wildfires. Although the word has been used to describe certain large fires, the phenomenon's determining characteristic is a fire with its own storm-force winds from every point of the compass. The Black Saturday bushfires and the Great Peshtigo Fire are possible examples of forest fires with some portion of combustion due to a firestorm. Firestorms can also occur in cities, usually as a deliberate effect of targeted explosives such as occurred as a result of the aerial firebombings of Hamburg, Dresden, and the atomic bombing of Hiroshima.