Most Read: Local

Posted at 10:30 AM ET, 04/20/2011

The width of a lightning bolt, part II

A lightning bolt exploded a long, thin strip of wood and bark from this poplar tree, spiraling from the top of the tree all of the way to the ground. The sap and moisture in the tree boiled with the heat of the lightning, causing bark and wood to literally explode along the path of the electric current.
Last year, I wrote a post about determining the width of a lightning bolt by using a tree that was struck by lightning as a measuring post. By measuring the burn mark on the wood I was able to determine that the diameter of lightning is roughly the size of a pencil to about an inch.

This winter, I found another tree that was struck by lightning. This tree’s measurements were consistent with what I had determined from the tree in my first post. However, whereas I found only the bark exploded on the first tree, both the wood and bark exploded on the second tree along the path of the electric current.

Read below to for more explanation and to see more photos.

A photo comparison of damage done to an oak tree (left) and a poplar tree (right) by a lightning strike. The width of damage is similar, but the poplar tree suffered damage to its wood and bark while the oak tree primarily suffered damage to its bark.
The tree in my first post is an oak and the tree featured in this post is a poplar. Lightning heats up the sap and moisture in a tree to the boiling point and literally explodes the water out of the tree. Perhaps the harder wood of the oak tree does not hold as much moisture as the softer wood of the poplar or is more resistant to the force of the exploding sap.

I’m not exactly certain why the poplar tree was more damaged than the oak tree, but it clearly illustrates how devastating a lightning strike can be to an object that contains water and can conduct electricity. This is a vivid reminder to all of us why it’s best to stay sheltered during a thunderstorm.

Long, thin strips of wood have been blown out of this poplar tree, caused by the explosive force of lightning boiling the tree's sap and moisture. closeup_std.jpg
A close up of the wood that exploded along the path of the lightning bolt. p1010246-2_std.jpg
The lightning bolt's point of entry into the ground. A strip of wood and bark were exploded from the top of the tree to the ground.

By  |  10:30 AM ET, 04/20/2011

Categories:  Latest, Photography

Read what others are saying

    © 2011 The Washington Post Company