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Tom Thomson in his dove grey canoe, packed
and ready to paddle away from his campsite |
Imagine that you are in Algonquin paddling on a quiet lake with your paint box looking for something to paint in the spring of 1913. You hear the roar of a jet plane as it taxis for lift off – a real problem in 1913! What do you decide to paint? Some decisions are easy - especially if you are Tom Thomson.
Tom had his standard small panels on board (so to speak) measuring 17.5 by 25.2 centimetres or almost 7 by 10 inches in his units (and mine). The entire cloud was too large to fit on the small canvasboard so he elected to make a composition out of the noisy part of the storm that was tracking left to right just in front of him and to his north.
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| Tom Thomson 1913 "Thunderhead" 7x10 inches |
Several miracles happened very quickly that afternoon in 1913. The first was that one of Canada’s finest plein air artists was paddling in the right place at just the right time. The second was that Tom had the required materials to record the unusual and rare event that he was about to witness. The third wonder was that the resultant record of the event was called “Thunderhead” and not “Tornado”. And perhaps the luckiest miracle was that Tom was not killed by this tornado.
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The Brodie Memorial Portrait" 1914 by
Owen Staples (1866-1949) funded
posthumously by his students,
fellow scientists and friends |
I don't believe that anyone really understood the true motivation behind this painting. Quite simply, the sketch is Tom's weather observation of an EF2 intensity tornado. Tom called his sketches "records" of what he saw. He collected these observations in the same way that his relation Dr. William Brodie collected specimens. Dr. William Brodie was a cousin of Tom's dad (Tom's father John was also something of a naturalist.). Dr. Brodie was 9 years older than Tom's father and one of the finest naturalists of the day. He was the director of the Biological Department of what is today the Royal Ontario Museum from 1903 until his death in 1909. Tom collected specimens with Dr. Brodie, who gave him the rudiments of a naturalist's training. Thomson learned from the passionate Dr. Brodie how to combine the keen and enthusiastic observation of nature with a sense of reverence for its mystery. He would need all of those skills on that afternoon in 1913.
Ernest Thompson, the award winning wildlife illustrator and naturalist was best friends with Willie Brodie Junior. Willie’s father was the same Dr. Brodie related to Tom Thomson. When Seton was preparing for a trip to the west in 1881, Brodie advised him to keep a daily journal saying “you will be sorry if you omit this, you will value it more each year.” Seton’s daily journals covered the following sixty years of his life and can be found in the American Museum of Natural History in New York. Tom Thomson most certainly received the same advice but Tom was more pictorial and used oils and brushes instead of words… but I digress – there is a tornado bearing down on us!
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| Tom Thomson at Lake Scugog ( T. H. Marten), Thunderhead Painting, Tornado Meteorology |
A tornado is associated with a supercell thunderstorm which is essentially an atmospheric engine that converts heat and moisture energy into motion. A supercell can be long-lived (at least an hour) and are highly organized and characterized by a tilted and rotating updraft. The rotating updraft is key and can be 10 miles in diameter and up to 50,000 feet tall. The following graphic is the one I used in my severe weather training sessions for
CANWARN and emergency response groups. I presented those talks for many years and enjoyed them immensely. The meteorology of a supercell is fascinating and requires considerable study which is beyond the scope of this story. This won't be on the quiz.
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| CANWARN Supercell Graphic |
There was certainly a supercell thunderstorm towering above Tom’s composition. Tom was too close and the cloud was much too huge to fit on the canvasboard. The accompanying graphic is from my PowerPoint presentation and all of those important features will eventually be described. This might take two or even three blogs to explain. In the presentation it takes about five PowerPoint slides full of arrows and sound effects. There is no requirement to make everyone a meteorologist but I do wish to relay sufficient information to convince you that Tom painted exactly what he saw – his art is a natural wonder.
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I used my paintings based on Tom’s sketches in the draft
of my “Tom Thomson Was A Weatherman” book. |
Tom was looking northerly due to the fact that most convective cells move from the southwest to the northeast over Ontario and specifically Georgian Bay and Algonquin. If this view had been looking toward the west or southwest, Tom probably would not have survived the “record”. This is Tom’s very accurate and detailed observation of a tornado. Most people probably would like to see a tornado before the die … but not just before the die. (I have used this line many, many times...) This tornado would have killed Tom had he been directly in its path and some of the finest art in Canada would never materialized.
The subject of the painting is actually the wall cloud underneath the rain free base of a large, supercell thunderstorm. These storms are more common than you might think and often go unobserved in the wilds of Canada. The tornado itself is hidden in the dark blue of blowing debris beneath the wall cloud. Remember that the tornado is the damaging wind and not the cloud. The striations in the edge of the wall cloud are pronounced and are the result of the strong associated rotation of the wall cloud. The roar of the tornado would have been tremendous but that could not be recorded in the oils.
Annotations Superimposed on Tom's Composition and Placed within the Appropriate
Portion of the Supercell Thunderstorm Conceptual Model
The thunderstorm updraft is directly above the wall cloud. If this was a cyclonic (counter-clockwise rotating) wall cloud which is by far the most likely, the winds in the foreground would be left to right. Air moistened by the rain that fell ahead of the tornado is drawn upward into the updraft. However this moisture laden air forms cloud at levels well below the lifted condensation level of the air mass. As a result, the base of the wall cloud associated with this high precipitation supercell, must be lower than the average base of the supercell. This is the main effect that forms the cloud lowering referred to here as the wall cloud.
I think that is enough for today... but stay tuned, there is much more to say about Tom's Thunderhead. I will explain all of the characteristic details that Tom painted that prove this was a tornado. Some of those features were not really understood until decades after that spring afternoon in 1913.
Warmest regards and keep your paddle in the water …
Phil the Forecaster Chadwick
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