Australia's unprecedented wildfires are supercharged thanks to climate change, the type of trees catching fire and weather, experts say.

And these fires are so extreme that they are triggering their own thunderstorms.

Here are a few questions and answers about the science behind the Australian wildfires that so far have burned about 5 million hectares (12.35 million acres), killing at least 17 people and destroying more than 1,400 homes.

"They are basically just in a horrific convergence of events," said Stanford University environmental studies director Chris Field, who chaired an internation...