There is a reason why standing under a tree during a storm is extremely dangerous. The electricity from lightning will find its fastest route to the ground. This means that any structure protruding from the earth provides a clear pathway. Trees are particularly inviting as the moisture in their trunks is a very good conductor of electricity. For lightning, travel by tree is like catching a bullet train.
The damage a lightning strike can cause varies. It depends on several factors, including: the type of tree, its height, the amount of moisture it contains, and the intensity and duration of the lightning strike.
Instant tree death
On average, a lightning strike produces 250 kilowatt hours of energy (enough to power over 50 houses for a day). A “cold” bolt (a high-intensity electrical current delivered in short bursts) striking the center of a tree can be powerful enough to split it in two, killing it instantly.
Moisture is often found along the inner bark of the tree. When electricity finds its way into these moist parts, the tree is vulnerable to extremely high temperatures. When enough heat builds up, the outer bark expands until it bursts.
This can also happen with unhealthy trees that have started to rot. With outer parts in a state of decay, moisture is concentrated at the center. Lightning striking the heart of one of these trees can send pieces of it flying in all directions.
The amount of moisture in the trunk (as well as the density of the foliage on branches) can determine whether or not a tree can catch fire. Less moisture and more foliage would make conflagration possible.
Another factor that may contribute to fire is the intensity of the lightning strike. Unlike the “cold” bolt, the low-intensity electrical currents of a “hot” bolt last longer and are more likely to set things ablaze.
Excessive rainfall somewhat protects a tree. Not only might it smother fires caused by a lightning strike, it also diverts the bolt from hitting the tree point-blank. Water from rainfall causes electricity to run down the side of the tree instead of the center. The lightning bolt may scar a tree, but otherwise leave little or no damage at all.
A tree that has attained even minimal damage is more vulnerable to other types of attack. A scarred tree is open to bug infestation, disease, and decay.
A large, strong-looking tree that has been struck by lightning may seem healthy. However, there’s no telling when it could fall. If the tree is in a residential area or a park, it could become a danger to anyone standing or walking beneath its canopy.
For inquiries regarding tree safety inspection and lightning protection, call Timberlane Tree Service Newmarket at (905) 778-9439 or Toronto at (416) 878-2108.