A wildfire is a large fire that rages across the landscape, threatening forests, homes and people.

Like all fires, the wildfire needs a source of fuel, such as tinder dry trees, or brush or grass, a source of oxygen (which is always in the air), and a source of heat to make the fuel get so hot that it gives off vapours which combine with the oxygen in the air to start a flame.

Once a flame has started, the flame itself makes the nearby fuel hot enough to produce more vapours and so catch alight, too.

What you see are the burning gases which contain tiny pieces of charred fuel that are so hot they glow yellow. The gases themselves are colourless.

Nature’s most common way of heating up fuel is a bolt of lightning. As it happens, bolts of lighting are very common in just those places where the ground is dry for long periods of time.

Of course, some wildfires are started by people, perhaps from carelessness, perhaps for a joke, perhaps out of spite.