A well grounded pine tree

Neil

by Neil Carleton

Even though a lightning flash is only about an inch, or 2.5 centimeters, in diameter, and lasts only a fraction of a second, it’s a tremendously powerful phenomenon.  A cloud to ground lightning flash occurs through a plasma channel in the air that can be 5 miles / 8 kilometers or more long.  Lightning can produce temperatures greater than 50,000 degrees Fahrenheit / 28,000 Celsius, and an electrical charge in the range of 100,000,000 volts.  Look out below!      

Standing tall in the forest, trees are natural lightning conductors.  The physics of a strike is fascinating, and best contemplated on site well after the event or, at the time, from the comfort of a safe location far, far away. 

While some trees seem to be completely unharmed by a lightning strike, others are heavily damaged or destroyed.  Pines are commonly hit by lightning.  The reasons include their significant height and a deep tap root that extends into the water table

A tall white pine at Fulton’s sugar bush was struck by lightning last fall.  It’s located only a ten minute walk from the pancake house, 399 Sugar Bush Road, Pakenham.  I’ll be happy to show it to you this Sunday, March 23, between 10:00 and 2:00, when I’m volunteering at the campfire with other members of the Mississippi Valley Field Naturalists.  http://www.fultons.ca/English/index.php
A tall white pine at Fulton’s sugar bush was struck by lightning last fall. It’s located only a ten minute walk from the pancake house, 399 Sugar Bush Road, Pakenham. I’ll be happy to show it to you this Sunday, March 23, between 10:00 and 2:00, when I’m volunteering at the campfire with other members of the Mississippi Valley Field Naturalists. http://www.fultons.ca/English/index.php

 When lightning strikes a tree, the path of least resistance to the ground can be outside or inside the trunk.  If, for example, there’s been a heavy rainfall during the storm, the flash may flow over the bark and into the earth.  If moisture is concentrated within dying or rotted sections deep in the trunk, lightning may travel through the interior and blow the tree apart.  Under other circumstances, the pathway could be just under the bark where the sap is located.

Although the lightning strike at Fulton’s would have been a spectacular sight, it would have happened too fast for our senses to fully comprehend at the moment.  With a channel of bark blasted from the tree, the first thing we might have noticed was all the steam.  Bark fragments were blasted well into the woods.  Interestingly, there was no scorching or burn marks.
Although the lightning strike at Fulton’s would have been a spectacular sight, it would have happened too fast for our senses to fully comprehend at the moment. With a channel of bark blasted from the tree, the first thing we might have noticed was all the steam. Bark fragments were blasted well into the woods. Interestingly, there was no scorching or burn marks.

A tremendous current flows through the flash channel when a tree is struck by lightning.  Where a strike travels beneath the bark, as it did in this case, the electrical resistance of the sap results in the near instantaneous creation of steam and a spectacular explosion.  In much less than the blink of an eye, the bark is blown outward from the lightning’s path.  Where the damage is shallow and narrow, it’s possible that the tree’s growth in subsequent years will cover the wound and result in a vertical scar.  If the root system has been damaged, the tree may not survive.

 

Although the explosion of bark, powered by rapidly expanding steam, would have happened in an instant, this part of the strike event would have occurred well after the lightning had grounded in the earth.  If you visit the tree, stand well back to see how the lightning followed the spiral growth of the tree from the west side near the top, to the north side at ground level.
Although the explosion of bark, powered by rapidly expanding steam, would have happened in an instant, this part of the strike event would have occurred well after the lightning had grounded in the earth. If you visit the tree, stand well back to see how the lightning followed the spiral growth of the tree from the west side near the top, to the north side at ground level.

Thank you to Shirley Fulton-Deugo for taking the time on a busy Sunday the other week at Fulton’s Pancake House and Sugar Bush to show me this remarkable tree.

 Do you have a notable or favourite tree?  Readers are invited to submit their nominations for an honor roll of trees in our area that could be featured in future articles.  You can contact me at 613-256-2018, <ve3nce@gmail.ca>, or Neil Carleton, 3 Argyle Street, P.O. Box 1644, Almonte, Ontario, K0A 1A0.  I look forward to hearing from you.

My volunteer columns started in March 2010, as print features, to support the tree planting and tree awareness initiatives of the Mississippi Mills Beautification Committee.  The contact for the Tree Committee is Ron Ayling, 613-256-4617.  In Carleton Place, the contact for the Urban Forest / River Corridor Advisory Committee is Jim McCready, 613-257-5853.

Until the next column, you’ll find me looking for and hanging out with shady characters.