Tom Thomson's "Spring" 1917

I have always admired this classic Thomson weather observation. It is characteristic of Tom's work as it quietly and accurately depicts everyday weather - spoiler alert, it is a warm frontal surface. It apparently struck a chord with another of my favourite artists, Lawren Harris.

In the spring of 1918 almost a year after the sudden passing of their friend, Lawren Harris and J.E.H. MacDonald met in the Studio Building. Tom's paintings from the Shack had been stacked in the Studio Building where he had painted with A.Y. Jackson, sharing Studio 1. Tom's tenure in the Studio Building ran from January 1914 to December 1915. The time spent painting in "The Shack" was more creative and was where Tom really shone. A lot of panels were moved from the Shack into the Studio Building.

Harris and MacDonald planned to sort through Tom's art, make comments on the back and distribute what they felt were the best examples of his genius. The ultimate goal was to ensure that Tom was acknowledged for his brilliance. It was a daunting task to shift through that pile of panels. It explains why so much was left unnoticed and unexplained. I must admit that I never wish to empower others with so much authority over my art but after death. That also discloses why my catalogue raisonné is so very complete in sharp contrast to the lack of detail in Tom's. I prefer to have the definitive voice on what I was trying to say and why. 

Spring 1917
Oil on wood panel 8 1/2 x 10 1/2 in. (21.6 x 26.7 cm)
Tom's Paint Box Size

Harris wrote "Save for Lawren Harris" on the back of this sketch. Apparently, Lawren saw something special in this weather observation as well. 

Tom's attention was always focused on the weather. Tom Thomson wrote to Dr. MacCallum on May 8th, 1917 that "the weather has been fine and warm". In Tom's last letter to MacCallum on July 7th, Tom complained that the weather "has been wet and cold all spring". As a true Canadian, Tom liked to talk about the weather but he painted it as well. This is the story of "Spring 1917" which was hidden in plain view with the deft strokes of Thomson's brush. 

Explanation of the Orange Sunrise and Red Sunset
Illumination Resulting from Diurnal Variations in
Atmospheric Particulates. 

Initially, one might scratch their head. Dawn was mentioned as the timing for this sketch. If only Tom had left a clue or two, that would have been helpful. The colour of the illumination was not strongly skewed to either the orange hues of sunrise or the reds of sunset. If anything, the clouds divulge a slight yellow tint so the timing of this sketch is likely early morning but not at the stroke of dawn. The "Belt of Venus" (see Tom Thomson's “A Northern Lake" Was the Belt of Venus Sunrise) was not evident as a result of the cloud cover. 

A narrow window in time and space allows the early morning sun 
to illuminate the scene before rising too high and thus becoming
blocked by the approaching and thickening cloud cover.
Note that I included the gravity waves of the wind waves and
the swells within the graphic deck of clouds.
Both are explained in more detail below. 

The distant hills were not yet illuminated so the sun was still rising but had not risen as high as the clouds. Later in the morning, the higher sun would be obscured by the thickening cloud deck. Tom had to be looking westerly early in the morning. 

The seasonal timing of spring is a certainty knowing where Tom was and what he was doing before the biting bugs emerged on May 24th, 1917. The leaves had not yet emerged and the landscape portion which was restricted to less than the lowest third of this panel was rather dark and drab. The front-lit colours of spring were not colourful as can be expected after a long winter. The birches alone revealed that the sunlight had to be on Tom's back. 

Tom was excited by the clouds and they were certainly the heroes of his scene. The altocumulus clouds were classic. If you hold your outstretched hand overhead, the convective elements of the altocumulus can be covered neatly by your thumb. This aptly named "rule of thumb" simply gauges how high (how far away) those cumulus elements are since convective bubbles are all about the same size in nature. The viewing distance is the only thing that changes the apparent scale of the convective elements. One can see that the overhead cumulus elements in Tom's painting are larger than those lower on the horizon. Tom accurately painted what he saw. 

Weather systems are swirls in the atmospheric ocean just like
 the swirls created by the stroke of the paddle in duckweed.
Tom was located at the gold star looking westward
(to the left in the above graphic). 

Cumuliform cloud shields are typical of an approaching warm conveyor belt during the convective seasons of the year (all seasons except winter). The conveyor belt conceptual model of mid-latitude weather systems is one that I have taught for several decades now. I keep trying to refine those methods and spread the joy of understanding the weather in terms of simple science. I do not give up easily.

The gravity waves superimposed on the altocumulus cloud elements reveal that the wind direction within that cloud deck was westerly. The waves on a lake respond to the wind in the very same way. The wavelength and amplitude of those gravity waves both increase with the wind speed. I used to teach the numerical correlation between the wind speed and the gravity cloud wavelength but I doubt if anyone does that anymore. 

Wave patterns are much easier to identify with backlit lighting. The alternating bands of light and dark clouds really stand out. The dark corresponds to thicker clouds associated with the updraft in the wave crest. The light bands identify thinner clouds with the downdraft flow of the wave trough. 

Dashed purple lines linking cumulus elements of roughly the
same size and brightness in an attempt to trace the updraft
region of the wind-induced gravity waves.

Front-lit gravity waves like those found in "Spring 1917" are much more challenging. The thicker cloud is brighter but marginally so compared to the thin cloud. Mie scattering of light from large particles throws most of the energy forward and away from the observer. Less energy returned to the observer through Mie scattering minimizes the contrast between thick and thin bands of the gravity wave clouds. If one links the adjacent, brighter altocumulus cloud elements, you can trace the wind wave crest and know that the wind in the atmospheric frame of reference must be perpendicular to that. 

Blue lines along the wave crests of longer wavelength
swells within the atmospheric ocean. 

A highlight of this sketch for me was noticing that there was another cyclic colour interval within Tom's sky. The darker purple/blue lines also appear at regular intervals. If one squints their eyes, this obvious wavelength becomes readily apparent and is unmasked from the details that Tom also recorded. These are gravity wave swells that have propagated great distances from where the atmospheric winds were stronger. The swell waves carry the characteristics of the source area where they were generated. These long wavelength waves were described in  "Wind Waves and Swells and Lines in the Sky" as well as in several other blog posts.

The wave pattern in the cloud is obvious but how can they be deciphered? The accompanying graphic attempts to illustrate small amplitude and short wavelength wind-driven waves superimposed on the larger amplitude and longer wavelength swells within the atmospheric ocean. The lifted condensation level for the air mass is described as Option 5 in the graphic so there is cloud everywhere even at the trough of the wind wave within the trough of the swell.  

The orientation of the swells compared to that of the wind waves must reveal the portion of the warm conveyor belt that was approaching Thomson. This in turn must reveal the progression of weather to expect. Using this bit of science was how I estimated Tom to be located at the gold star relative to the warm conveyor belt in the accompanying graphic as well as the above graphic - between the anticyclonic and cyclonic companions of the warm conveyor belt. 

The reality is that if you paint what you see, the science must always be correct. Tom was painting the bottom of the elevated warm frontal surface. If we estimate the height of that cloud above Tom and apply the standard slope of a warm frontal surface as being 200:1, Tom could have estimated how far to the southwest the surface warm front might have been. Most people do not care but Tom probably did. Those altocumulus clouds were probably nearly 12 thousand feet above Tom... the math is straightforward. That number of feet above the ground was about 2 miles so the surface warm front was approximately 2 times 200 or 400 miles away. By the way, please let me apologize for my reckless use of measures ranging from Metric to British to the size of your thumb - it reflects how I see the world.  

Spring 1917
Oil on wood panel 8 1/2 x 10 1/2 in. (21.6 x 26.7 cm)
Tom's Paint Box Size  

So the story behind "Spring" actually is more interesting than just a cloudy sky. Lawren obviously appreciated that story as well. 

Inscription verso (on the back): in graphite, This sketch was painted / in the spring of Thomson's drowning / J. MacCallum; in graphite, J + H (circled); in graphite, No. 3 Mrs. Harkness; in red, 21; in black paint, S.B.; in L. Harris's handwriting, under label, Save for (crossed out) lawren Harris (circled) Art Gallery of Ontario, Toronto (855). The back of this panel would be interesting to see! Lawren was overruled but by who? The inscriptions on the back of the panel might provide the answer to that mystery but it is a bit cryptic and one cannot be certain.

"Spring 1917" as it would have appeared in
Tom Thomson's paint box

Many panels by Tom Thomson bear the name "Spring 1917" or very similar variations. It was the most prolific period of his career. The provenance of this painting surprisingly does not include Lawren Harris. The painting went from the "Estate of the Artist" to Elizabeth, Tom Thomson’s eldest sister. Recall that Elizabeth's husband was Thomas “Tom” J. Harkness who was appointed by the Thomson family to look after the affairs of Tom’s estate. From Elizabeth, aka "Mrs. Harkness", the painting went to the Art Gallery of Ontario, Toronto (855), a Gift from the Reuben and Kate Leonard Canadian Fund, 1927. 

The story behind a painting can be as interesting as the art itself. 

Warmest regards and keep your paddle in the water,

Phil Chadwick

PS: Tom Thomson Was A Weatherman - Summary As of Now contains all of the entries to date.