Tom’s motivation to “record” this particular observation – the striking cloud structure and sunrise light.
The low horizon identifies another of Tom’s skyscapes. I painted my interpretation on a piece of basswood plank measuring only 4 by 5 inches. Tom's sketch was on a piece of 7 by 10 inch canvas - smaller than his regular paint box size of 8.5 by 10.5 inches. That is unusual and there is probably a story behind this smaller size - I just do not know what that tale is.
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| Tom Thomson's sketch for "Morning Cloud" Fall 1913 Oil on canvas 7 x 9 15/16 in. (17.8 x 25.3 cm) Smaller than Tom's Paint Box Size Art Gallery of Ontario, Toronto (70/368) |
- I am really glad “morning” appears in the title leaving little doubt as to the timing of this plein air painting.
- The clouds are definitely “backlit” with the edges being much brighter than the interior. For an explanation of front-lit and backlit see "Where is the sun?".
- The sky has a distinct orange hue timing this sketch as early in the morning through the application of Rayleigh scattering principles. Tom painted looking toward the sun but that was not a concern since the sun was still lower than the cloud edge. Tom would be finished the sketch before the sun cleared the top of the cloud.
- The distant hills were backlit and in shadow thus lacking in colour.
- There was a “white line” on the distant shore indicating that Tom was looking toward the dominant light source - sun glint. I described the optics of the white line in "1207 Blue Line" but may dedicate another blog and more graphics in the future.
- The knife edge of the cloud is fundamental to locating Tom in relation to the storm. The cloud was altostratus. Altostratus is located in a moist and stable atmosphere. The altostratus indicates rising air in the atmosphere and this must be associated with a retreating low-pressure area. The sharp edge observed by Tom separates the moist air of the warm conveyor belt from dry. This sharp edge occurs in two possible areas of the conveyor belt conceptual model and these options will be explained below.
- Tom was looking southeasterly at that autumn sunrise.
- The wave action was from the observer's right shoulder making it a west-to-northwesterly surface wind. This would be consistent with cold air advection in the wake of a large low-pressure area.
- Examination of the wave action suggests that the waves grow larger with distance. This is the opposite effect that one would expect as objects get smaller with distance. Larger waves in the distance are quite consistent if one is painting from a forested shore. I was using a high-resolution scan of the painting to reach this conclusion. I might be reaching here and reading something into the brush strokes but it is okay to suggest the principle.
The forecast for “today” was going to be sunny but cooler. The temperature would be slow to rise during the day as the heating from the sun would be negated somewhat by the cold air advection. The northwesterly breezes would help to keep the last of the deer flies and biting insects down. They would also dry out his tent and clothes. Turbulent stratocumulus would probably develop parallel to the gusty winds but they would set with the sun in the evening.
To be complete, there are two locations on the back edge of a storm where this cloud pattern might be witnessed. One view is looking more southeasterly at the comma head of the storm. The second is gazing more toward the east and the retreating cold front. Spoiler alert - I am trying to be complete but if you find the next few paragraphs a bit heavy, jump to the Most Probable Creative Scene Investigation (CSI) Solution.
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| Two potential locations for Tom Thomson in order to view this cloud structure within a retreating autumn storm |
The Comma Head Solution
In the early days of satellite meteorology, the cloud pattern of a typical storm was described as a comma, complete with a head and a tail. The dry slot is where the jet stream cuts into the back of the comma head. The concepts of conveyor belts and deformation zones would be developed soon thereafter.
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| The Comma Pattern and the Beginning of Satellite Meteorology - Slide from another PowerPoint Presentation |
The flow described by confluent asymptote "A" in the accompanying graphic would possess a very sharp northwestern edge - as it would at "B". With the storm exiting toward the east, location A in the graphic is the only option for Tom's location. If Tom was at B, the weather was still approaching his easel.
The Cold Frontal Option
In this option, Tom would be looking at the western flank of the warm conveyor belt rising along the constant energy (isentropic) surface. The sharp cloud edge would be the result of the wind increasing in speed towards the local wind maximum that creates the dry slot in the comma pattern of the cloud. There are more likely to be multiple layers of cloud in this "cold frontal" option. Essentially the cold front is the surface manifestation of the three-dimensional deformation zone skin that encases the warm and moist air. Low cloud is also more likely to be associated with the surface cold front and for these reasons, this is the less likely option in my opinion.
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| The Cold Frontal Option would place Tom near A in this graphic |
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| This would be Tom's view looking eastward |
The Most Probable Creative Scene Investigation (CSI) Solution
It would have been easy to discern the weather situation if I had been painting with Tom that morning. If the cloud was drifting slowly northward to the left, we would have been looking at the back edge of the surface cold front. If the cloud was stationary or even drifting slowly to the right, we would have been looking at the confluent asymptote hemming in the comma head upstream from the col. I think Tom would have wanted to know which was the case and this may explain why he recorded this weather-scape. Weather is always interesting and it impacts our daily activities especially if we are plein air painting or canoeing.
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| PowerPoint Slide from Tom Thomson Was A Weatherman employing my 4x5 inch basswood slab version |
To summarize, the morning cloud was the retreating deformation zone of the comma head cloud edge of an intense autumn low-pressure area tracking eastward across Algonquin. Cooler and blustery west to northwest winds were blowing across the waters of the lake which would have been still warm after a summer of heating. Tom was enjoying the dramatic sunrise behind the knife-edge of cloud and looking easterly (110 degrees) toward the rising sun.
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| PowerPoint Slide illustrating the use of the time of year and the location of the sunrise to adjust the viewing angle of the plein air painting. Tom was more likely to be fishing in July so an October plein air adventure and angle of view would be probable. |
Note that the exact date of the painting would allow some further refinement on the direction of view. The location of sunrise and sunset given the day of the year is an astronomical certainty.
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| A Singleton afternoon view of the retreating "comma head" of a low-pressure area and the associated layers of cloud. This cloud is clearly front-lit and bright as contrasted with Tom's sunrise backlit and darker cloud. |
The above photographic example of a similar cloud pattern was looking east at the deformation zones of a retreating summer rain storm at 6 pm on June 13th, 2014. There were two layers of moisture hemmed in by deformation zones caused by the strong circulations around that low-pressure area. Over the course of almost two days, this storm dropped 55 mm of rain at Singleton Lake. It could have been a similar event for Tom back in 1913. This photo would be called “The Evening Cloud” although I have not turned it into a painting.
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| The Studio Building, 25 Severn Street Studio 1 on the ground floor |
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| Morning Cloud Alternate title: Dawn, Smoke Lake and Morning Cloud Winter 1913–14 Oil on canvas 28 3/8 x 40 1/16 in. (72 x 101.8 cm) |
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