The below photograph shows thick smoke billowing from the West Fork Complex Fire burning in southern Colorado.
The image was taken by an astronaut aboard the International Space Station on June 19, 2013.
NASA Earth Observatory says "The West Fork Complex is a combination of three fires: the West Fork fire, the Windy Pass fire, and the Papoose fire."
Lighting is blamed for igniting the first of the three fires.
The West Fork Complex fire is burning through beetle-damaged stands of spruce.
The stands of dead trees allowed the fire to burn hotter than the portions of healthy forest in the path of the flames.
NASA Earth Observatory says the fire burned "so hot that it spawned numerous pyrocumulus clouds—tall, cauliflower-shaped clouds that billowed high above the surface. Pyrocumulus clouds are similar to cumulus clouds, but the heat that forces the air to rise comes from fire instead of sun-warmed ground."
These clouds can inject the ashy smoke high into the atmosphere where winds can spread it far across the globe.
Satellite observations showed the smoke reaching European airspace by Monday, June 24th.