I guess the majority of these fires are caused by lightning. There are some 16 million lightning storms in the world every year[1], or about 44,000 every day.

I guess the majority of these fires are caused by lightning. There are some 16 million lightning storms in the world every year[1], or about 44,000 every day. An interesting video of lightning seen from the Space Shuttle during night time orbit of Earth: http://www.youtube.com/watch?v=i6RxE-f2iyQ http://www.youtube.com/watch?v=i6RxE-f2iyQ The Wired video is also interesting because it shows the expanding and contracting areas of frost and vegetation. [1] http://en.wikipedia.org/wiki/Lightning http://en.wikipedia.org/wiki/Lightning