Today’s Wonder of the Day was inspired by Gemma. Gemma Wonders, “how lightning sets a tree on fire” Thanks for WONDERing with us, Gemma!
Pow! Bam! Kaboom! No, those aren’t the captions of cartoon fistfights. They’re the sounds we often hear overhead from the clouds that accompany thunderstorms.
Of course, when you hear thunder, you look for . . . lightning! Maybe you even count the seconds between a clap of thunder and a flash of lightning. This can help you measure how close or far away the lightning occurs.
What exactly is lightning? Quite simply, it’s a bright flash of electricity. It can occur within a single cloud, between clouds, and between a cloud and the ground. The latter, often called cloud-to-ground lightning, is what we commonly think of as a lightning bolt that we see during a thunderstorm.
What causes cloud-to-ground lightning? Small particles of ice collide within thunderclouds, causing an electric charge to build up. Objects on the ground, especially taller things like mountains, buildings, trees, and even people, can also build up an electric charge. When these charges meet, they connect. Electric current flows rapidly from the cloud to the ground. This causes a lightning strike.
Have you ever experienced static electricity? It has a similar cause. For example, walking across a carpet makes you build up electric charge. When you touch something metal, you may feel a shock! That’s static electricity moving between you and the object.
A flash of lightning is only a few inches wide. However, it appears much larger to the human eye. It can also be very dangerous—even deadly. There is a great deal of electricity in a flash of lightning, and it’s also very hot. A single bolt can generate temperatures of about 54,000º F. That’s about six times hotter than the surface of the Sun!
So, what happens when that powerful bolt of lightning hits an object on Earth? In particular, what happens when lightning strikes a living tree? The type of tree, its overall health, and the amount of moisture it contains all affect how the tree is impacted. Of course, the intensity of the lightning itself also plays a role.
Much of the damage is a result of what happens when the moisture inside a tree meets the super-hot temperatures caused by lightning. A tree’s moist tissues often sit just below the outer layer of bark. This is why some lightning strikes result in the bark of a tree appearing to explode in large chunks.
If the outer layer of bark is soaked from heavy rainfall, the lightning may travel along the outside of the tree to the ground. This results in little damage. At other times, though, intense lightning bolts may split trees in two and cause them to burst into flame from the inside out.
A tree that has been hit by lightning may live for many years. Others might need to be cut down if they pose a danger of falling on people or property. Some large trees have been known to have been hit by lightning on many separate occasions.
If a tree struck by lightning doesn’t catch fire and burn to the ground, it may survive for quite a while with its injuries. Lightning-damaged trees, however, will often be more susceptible to damage from insects, disease, and decay.
Have you ever seen a tree that’s been struck by lightning? How about other objects? Lightning may be dangerous, but it’s also a very interesting weather phenomenon! Now you’ll know what causes these bright flashes of light during the next thunderstorm.
Standards: NGSS.PS3.C, NGSS.ESS2.D, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.SL.1, CCRA.W.2, CCRA.W.4, CCRA.W.9, CCRA.W.10, CCRA.L.1, CCRA.L.2