Lightning Scar on Cottonwood Tree
August 24, 2009
In Arlington Heights, Illinois, the mature cottonwood shown above was struck by a lightning bolt on May 6, 2004. The lightning hit near the top of this approximately 80 ft (24 m), 60 year old tree. The tree’s sap was heated to steam by the powerful lightning and blew a substantial amount of bark out into our residential street. One piece landed in my front yard about 150 ft (46 m) away. Notice the pipe just in front of the tree. This is the water turn-off pipe, which Arlington Heights uses to control the flow of water to the houses along the community streets. The lightning discharge was grounded at the pipe, severely burning the grass -- long since healed. However, the tree has not fared as well: observe the three foot (nearly one meter) wide patch of missing bark narrowing toward the first set of branches. Since electrons flow typically on the outside of a conductor, the huge electrical discharge did its damage primarily on the outside of the tree. The lightning scar continues to the top of the tree but is obscured during summer by ample foliage.
I’ll not soon forget this storm. It occurred in the middle of a warm afternoon while my family was watching a movie that had a cannon battle scene between two sailing ships (“Master and Commander: The Far Side of the World”). One of the cannon blasts seemed all too loud and real. After the storm subsided and the movie ended, I saw the bark shards first and then followed the debris back across the street to the damaged tree. A few years ago, another large section of bark fell away, revealing the total extent of the damage you can see in this picture.