Wildfires spread by radiation, convection and firebrands.

Radiation is the process by which wildfires heat up the surrounding area. This is similar to the way a radiator heats a room during the winter but at considerably higher temperatures. Radiant heat from a wildfire can ignite combustible materials from distances of 100 feet or more. (Photo shows wildfire and illustrates how radiation is heating up the surrounding area.)

Flames often occur within columns of heat known as convection columns and can ignite anything flammable they contact. Typically, the flames in a convection column rise straight up, while cooling air descends and hot air rises in a cyclical pattern forming a column of looping heat.

However, winds can cause flames to rise diagonally, or even nearly horizontally, extending the reach of the flames. (Photo shows illustration of convection currents.)

The third way a wildfire spreads is through firebrands, which are burning materials that are blown by wind from one place to another. Winds can blow firebrands more than a mile away from their source, starting new fires wherever they land. (Photo shows firebrands being blown by winds.)