
I was just curious so I thought I'd post in case you were too
I got this from Wikipedia
Lightning is an atmospheric discharge of electricity, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms.[1] In the atmospheric electrical discharge, a leader of a bolt of lightning can travel at speeds of 60,000 m/s, and can reach temperatures approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into petrified lightning, known scientifically as glass channels or fulgurites which are normally hollow and can extend some distance into the ground.[2][3] There are over 16 million lightning storms in the US every year.[citation needed] The chance of being struck by lightning is approximately 576,000 to 1 and the chance of actually being killed by lightning is approximately 2,320,000 to 1.[citation needed]
Lightning can also occur within the ash clouds from volcanic eruptions, or can be caused by violent forest fires which generate sufficient dust to create a static charge.[1][4]
How lightning initially forms is still a matter of debate:[5] Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, friction, and atmospheric pressure) to the impact of solar wind and accumulation of charged solar particles.[6] Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud, thus assisting in the formation of lightning.[6]
View here for all it has to say on lightning
http://en.wikipedia.org/wiki/Lightning