Tom Thomson's "Georgian Bay, Summer " 1914

Not every Tom Thomson sky is a storm. But every sky still has a story to tell. This is a subtle tale of altocumulus cloud lines shaped by the atmospheric frame winds...

The summer of 1914 was one long adventure for Tom Thomson. Tom spent two of those summer months at MacCallum’s cottage in Go-Home Bay, Georgian Bay. It was there that he recorded this weather observation before he escaped back to camp in Algonquin in early August.

Georgian Bay, Summer 1914, Oil on panel, 8.5 X 10.5 inches

On the back of the unsigned painting is some very important information. 

"Inscription verso: u.edge: AM / View from Pine Islands looking west toward Hope island / Beckwith & the watchers - July 1914 - about 6 pm / MacCallum; l.r.q., VIEW FROM PINE ISLAND 13;* L.R.Q., No. 142"

A Tom Thomson expert and a friend of mine commented: "MacCallum wrote the identification of time and place when he and J.E.H. Macdonald sorted and identified the works left in Thomson's (shack) studio after he died.  The AM might have been initials of someone to whom MacCallum thought the painting could be sold.  Other notes and numbers may be from times the painting was exhibited - apparently galleries often numbered the paintings in their shows or sales.  u. edge - upper edge; l.r.q. - lower right quarter.  There is an estate stamp, too."

The information that makes sense to me allows one to fairly accurately place where Tom Thomson was standing when he completed this sketch on the July evening in 1914. Tom was probably located on the southern most of the Pine Islands looking toward the southwest. Dr. McCallum identified the time as being "about 6 pm". All of the islands in that field of view can be accounted for using Google Earth. 

The story written in the sky is subtle. I considered a couple of other possible options but the following fits the most pieces into the meteorological puzzle. First, it is important to recognize the altocumulus cloud as being within the free atmosphere, removed from interactions with the earth. The meteorology that needs to be applied is the Conveyor Belt Conceptual Model and not that of the Planetary Boundary Layer. 

Rising air is required to to sustain the altocumulus clouds. If I take out my trusty Coriolis Hand (your right hand if you are in the northern hemisphere)  and point your Coriolis Thumb upward in the direction of the rising air, your fingers must curl in the direction of the air flow. The cyclonic companion of the deformation zone was overhead. Notice how the cloud amounts diminish to the west? This can only be a single location within the Conveyor Belt Conceptual Model. All of the rest follows from this bit of knowledge. 

A summer storm was exiting southern Ontario to the east. Tom Thomson was painting the "hang back" portion of the cyclonic circulation around the low pressure area. The most distant band of altocumulus was the cyclonic mid level confluent asymptote of the deformation zone - the green arrow turning cyclonically southward from the col in the following graphic.

I attempted to recreate the weather scenario as best fit the cloud patterns. The low and strong winds were well east of Go Home Bay but the hang back deformation zone still trailed to the west of Christian Island. Fair weather was on the southwestern horizon. The strong winds in the core of the storm were still shaking the inversion of the warm conveyor belt like a blanket. Those gravity waves were the swells that Tom observed. 

The banding in the clouds contained within that deformation zone was the result of atmospheric swells that originated from the centre of the storm far to the east. These clouds are all at nearly the same mid level in the atmosphere. 

The atmospheric swell is the large purple wave in the accompanying graphic. The smaller amplitude and shorter wavelength wind waves are typically  superimposed on the swell and can create some interesting patterns. In the following diagnosis of Tom's observation, the swells are the large bands of cloud areas. The crest of each swell is identified by thicker cloud. The trough of each swell has less cloud or even clear skies depending on the level of the lifted condensation level. 

Swells occur in all fluids but have been largely ignored in the atmosphere. I have been attempting to change that for decades... without much success. I never stop trying though. 

Swells from a fishing boat that crossed the south shore
of Singleton Lake about 15 minutes previously

The wind waves in the portion of the swells within the red circle in the accompanying graphic are perpendicular to the orientation of the swells. The wind waves could explain the patterns in the altocumulus although Tom did not record them as neat and regular waves. I doubt that even Tom noticed the secondary wind waves that chopped the altocumulus into periodic chunks. I connected the cloudier bits with the dashed grey lines but I am far from convinced and I can be pretty gullible! A few cloudy areas line up but that could just be chance!

Try to Connect as Many Wind Wave Crest as Possible ... it is feasible but quite unlikely
that Tom would observe and then 
record this level of cloud elemental detail. 

“Georgian Bay” was challenging to diagnose - there is a lot of science in those brush strokes. More than half of the small, plein air panel belongs to the sky and the weather. The selected name that focusses on the lake is really not  appropriate. The motivation for Tom to paint the patterns in the sky cannot be found in "Georgian Bay".  

The original can be seen at the McMichael Canadian Art Collection in Kleinburg (1974.9.7). Upon Tom's death in 1917, this painting became the property of Tom's eldest sister, Elizabeth Thomson Harkness of Annan and later Owen Sound. The painting was then passed to Margaret, the ninth of the ten children born to John and Margaret Thomson. The families were big in those days!

Margaret grew up in Leith, near Owen Sound and enjoyed the same upbringing as Tom surrounded by music and the arts. Margaret Thomson Tweedale had moved to Toronto by the time she gifted "Georgian Bay" to the McMichael Canadian Art Collection in 1974. Margaret passed in 1979 but remained  fiercely protective of her brother Tom's reputation.  

I try to carry on with Margaret's protection of Tom in my own small way... it is important to know the full story that inspired Tom's art and I can help with that ... 

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick

PS: For the Blog Version of my Tom Thomson catalogue raisonné, Google Search Naturally Curious "Tom Thomson Was A Weatherman - Summary As of Now" or follow this link “http://philtheforecaster.blogspot.com/2022/10/tom-thomson-was-weatherman-summary-as.html”