Ember attack

An ember attack is when, during a bushfire, burning twigs, bark fragments, moss or leaves become temporarily airborne and are carried by winds in a cluster.
Despite characteristics of an efficient embers are not directly known, trees bark is generally considered the most dangerous source in Australia. This led to the definition of a categorical classification (Bark Hazard) used to evaluate the potential threat of ember attack.
The Stringybark species of Eucalypt is particularly notorious for contributing large flaming sections of bark that due to their size, weight and shape, can be carried up to several kilometres away. The movements of embers from a bushfire are the primary cause of spot fires, which contribute to the continued spread of a bushfire.
Fire spotting due to embers.
Ember attack can ignite additional fires ahead of the main fire front. 
This process is called fire spotting and occurs predominantly with two distinct spatial patters:
The likelihood of ignition caused by embers is a function of several environmental variables and ember characteristics, including:
Effect on firefighting.
Ember attacks have the potential to start small fires ahead of the main fire trapping firefighters between the two fires. They can also lodge themselves within firefighting equipment, clothing and vehicles.
In late 2019, a fire truck caught fire in an ember attack in the Currowan bushfire in New South Wales, Australia. Fortunately, the fire team made it out alive. Ember attacks are particularly dangerous to an individual's exposed skin and face.
Effect on property.
Embers account for 75-80% of total property loss in Australia
Direct ignition of structures due to ember is possible, for example:
However, the majority of property loss happens due to secondary ignitions, for example:
Embers commonly cause house loss up to 500 meters from the fire front, and in exceptional circumstances up to kilometers
In Australia, evaporative air conditioners are known to ignite from ember attack. Ember attack causes the filter pads from evaporative AC to ignite, and the fire spreads through the roof space destroying the home. Ember guards (also known as ash screens) are recommended to protect air conditioners from ember attack.