We typically only hear about instances when lightning strikes people and buildings. However, our arborist can tell you that trees are the most common victims. Most lightning bolts pass through trees on the way to the ground. This is because trees contain a lot of water and water is a better electrical conductor than air. The tree trunk in particular contains a high concentration of water near the cambium – just under the bark. As the electricity from the lightning surges through the water in the tree trunk, it causes it to boil explosively, blasting off the bark, and sometimes throwing pieces over a hundred feet.
Although a typical lightning bolt contains 250 kilowatt hours of electricity, it is the duration of the lightning bolt that determines how destructive it will be. “Cold” bolts are characterized by high electrical current and extremely short duration. One of these penetrating to the heart of a tree can convert it to kindling instantaneously. “Hot” bolts are of lower electrical current but slightly longer duration. They are likely to set things on fire. In fact, this is the source of approximately 7,500 forest fires in the US each year.