My first diagnosis of "The Hill in Autumn" really troubled me! Some subtle inconsistencies bothered me enough that the story did not get published in the first go-round. The puzzle pieces did not fit together as nicely as they should. Was Tom looking east or west? Were the coniferous trees in the centre of the painting in shadow (looking easterly), or were there no deciduous trees there because of soil conditions?
The illumination of the scene was sufficient to bring the colours out of the forest. The sun had to be a least a bit on Tom's back or at least overhead. The clouds were no problem, but I needed to be certain of the direction of view! Was that storm coming or going? Let me explain... please.
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| "The Hill in Autumn" Fall 1914 Oil on composite wood-pulp board 8 7/16 x 10 1/2 in. (21.5 x 26.7 cm) Tom's paint box size, 1914.72 |
My friends Jim and Sue came to the rescue again! The "paddle in the water explorations" of the Waddingtons were instrumental in correctly solving the riddle of Tom Thomson's "The Hill in Autumn" from 1914. We must also acknowledge Tom Thomson for painting exactly what he saw. Tom did not make anything up!
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| The Waddington image from Broncho Island on the left with "The Hill in Autumn" to the right. |
A picture is indeed worth a thousand words. Tom, along with pretty much every artist I know, will distort the subject to better fit the size of the painting surface that they have available. Tom scrunched the horizontal dimensions, but the details remain unmistakable.
The photo was taken looking west. The topography matching Tom's painting was unmistakable.
The wind spins the paper towel rolls in the sense indicated. The "cloudy" white roll to the left (looking downstream) of the local wind maximum spins cyclonically (the red arrow) - the thumb of your Coriolis hand will be pointing up. The "blue sky" roll to the right (looking downstream) of the local wind maximum spins anticyclonically (the blue arrow). Your Coriolis thumb will be pointing downward.
Here is that same view at noon the following day. Winter had returned to Singleton. The intensity and speed of the weather system could be inferred from those lines in the sky. I spend a lot of time looking up at the sky - time well wasted!
Jim writes further: "I have since learned from the Voyageur Outfitting site about their island retreat. The Island was once a 'camp' of Tom Wattie, who was an Algonquin Park ranger from 1900-1931. Tom Thomson was also a park ranger at this time and became good friends with Wattie, visiting him often at his camp, now known as the Algonquin Island Retreat."
Bronco Island is on Kawawaymog Lake, which was formerly known as Round Lake.
Jim and Sue also observe: "Thomson probably wasn't in the middle of the lake like us but was on one of the islands, presumably Wattie's".
With the viewing direction firmly established, I could make progress on the meteorology in Tom's painting. The skyline was at the lower third of the small panel, so the subject that caught Tom's attention was most certainly the weather.
It was a windy day as well when Tom made his weather observation. Mares' tail cirrus was overhead in an azure sky. Recall that backlit cirrus is not dark in its centre like more opaque clouds. Cirrus ice crystals are just not present in sufficient density to block the sunlight.
The shape of the cirrus cloud elements is all we need to establish both the average wind and the deviations from that mean, which sculpt those intricate patterns. It is easiest to just witness the cloud drift across the sky to establish the average wind. The entire mass of moisture simply moves along with the mean flow. For example, I was able to easily follow the motion of the mares' tails depicted in the following graphic, so I knew the direction of the average wind. That is not possible with a still image, but the shape crafted by the relative winds can still reveal the mean.
The cloud shape revealed that the average wind at cloud level would have been from right to left, as depicted in the painting and in the actual clouds I photographed. Thus, the upper winds were from the north since Tom was looking toward the west (thanks to Jim and Sue). The following graphic details these deductions and will serve as an introduction to cloud watching. Actual mares' tail cirrus are included along with Tom's interpretation of what he witnessed.
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| See "A Jet Streak with a Paddle" for an explanation of the atmospheric frame of reference. |
The following graphic applies the above concepts to the still images of mares' tails in Tom's "The Hill in Autumn". Remember that clouds are three-dimensional and exist through a depth in the atmospheric ocean, although we only witness planar views, especially in the painting. For example, the green col symbol at the leading edge of the cirrus is probably at a higher level than the swirls sketched. The col and lines of the deformation zone conceptual model must be continuous in the view of the processes on a piece of paper.
Try to visualize the swirls as three-dimensional vortices tilted forward with the strong winds along. The col at the nose of the cirrus would be as sketched in the graphic. Any ice crystals wafting groundward would be caught in the vortices that flank the local wind maximum embedded within the mean flow. These processes neatly explain the swallow-like appearance of the cirrus uncinus, which is what really attracted Tom's attention in the first place!
My COMET friends in Boulder could manufacture a wonderful animation of this dynamic structure and make it come alive! For now, please try to play that image in your mind using your Coriolis hand. My efforts to explain this in the weather centre were typically unsuccessful, but I never give up. Also see "A Closer Look at Lines in the Sky" which is one of several explanations of deformation zones and the important role that they play in understanding moisture patterns in any fluid.
I was in the Studio and decided to manufacture a three-dimensional representation of the planar view of mares' tail cirrus. In the image, using my Studio step stool, the wind increases with height from the floor through steps one and two. The strongest wind is in the direction of my mahl stick (circa 1966) positioned at the very top of the stool.
The wind spins the paper towel rolls in the sense indicated. The "cloudy" white roll to the left (looking downstream) of the local wind maximum spins cyclonically (the red arrow) - the thumb of your Coriolis hand will be pointing up. The "blue sky" roll to the right (looking downstream) of the local wind maximum spins anticyclonically (the blue arrow). Your Coriolis thumb will be pointing downward.
The wind is strongest at the level of the mahl stick, so both of these rotating vortices are tipped forward with the wind. The moisture is also advanced furthest downstream at this level, represented by the cushion at the tip of the mahl stick.
Now visualize the ice crystals from the cirrus caught up in these vortices drifting toward the earth - gravity gets us all eventually! I draped the towel sheets to try to represent how that might look.
The final visualization is a quasi-horizontal cross-section through the towels and mahl stick, integrating what one would see from the ground, seeing all of the different layers of the three-dimensional moisture.
Now back to "The Hill in Autumn". The wind direction at the surface can be quite different from that revealed by the cirrus above 20,000 feet. In this case, though, we can be quite certain that the winds were brisk and chilly northwesterlies.
The blue skies and clear visibility were characteristic of a ridge of high pressure over Tom. Air generally subsides ahead of a ridge, and the pressure at the ground rises with the fair weather. That's why people have barometers on their walls. The air was dry, and there was not even a hint of cumulus clouds under the sunny skies.
Winds are generally calm in a high-pressure centre. The wind speed inducing the waves that Tom painted would only be found in the anticyclonic flow ahead of the ridge or after the ridge had passed. The former is certainly the case in this situation as the cirrus is not a large deck of cirrostratus but rather isolated, thin mares' tails. Cold air advection is also much more likely to bring the momentum of stronger winds aloft descending to the surface. Recall the constant energy trajectories that air parcels follow, sloping downward to the ground as they head south. See "Isentropic Surfaces - Science and Art Merges" for more explanations and details.
The other important part of this puzzle can be seen on the western horizon. Bands of rose-coloured cloud stretch along a deformation zone that encloses the warm conveyor belt of an approaching weather system. Tom painted bands of cirrostratus within gravity wave swells being stretched by the deforming flow.
Like in the ocean, the atmospheric swells propagate outward from the source but are most significant in the same direction as the strong winds that generate them. Using the westerly nature of the jet stream and this fact would be enough to realize that Tom had to be looking toward the approaching storm. I felt that the swells in the cirrostratus might not be sufficient evidence, even though I was convinced. I can be pretty gullible.
Separately, each puzzle piece described above cannot fully diagnose the weather pattern. However, the pieces can only fit together in one way to make meteorological sense. The following graphic summarizes how the mares' tail cirrus, strong northwesterly upper winds, brisk northwesterly surface winds and distant swells of cirrostratus must fit together. It may not be rocket science, but I still think the story is a blast.
A similar parade of weather occurred on April 7th, 2025. The sky overhead Singleton included a few patches of mares' tail cirrus, which I watched to establish the northwesterly flow aloft in an earlier graphic. Some cirrostratus was low on the horizon but too subtle for an interesting picture. The sky changed dramatically in just an hour or two. The approaching storm was racing toward the east. The following graphic describes those lines in that sky. Weather is important.
I consulted with my weather friend Johnny Lade. John made the following excellent observations:
"I always look for the western horizon. Maybe from thirty years of doing weather observations and looking for a deformation zone. In my ground school teaching, I always told my students to notice trends. Always watch the weather on TV and feel the weather.
So, in your description, the first day of a high is windy, too windy for my pilot friends to go up and do cross countries. The second day and into the third day will be fine before the strong westerlies develop. I have a barometer on the wall by the door in my house to follow trends.
I have favourite clouds. This painting has mare's tails and invading altocumulus! "
John and I spend a lot of time marveling at the weather. We are perpetual students and always happy within our natural laboratory.
The "The Hill in Autumn" was another painting comprising the very tall stack of panels salvaged from Thomson's Shack in the spring of 1918. Harris and MacDonald enjoyed a relatively easy time naming this work. The painting depicted a prominent hill, and the deciduous trees were the colours witnessed in autumn. There was no need to discuss the clouds in the sky even though they were the subjects of Tom's weather observation.
The determined investigations of Jim and Sue Waddington were essential to unravel the real story behind Tom Thomson's "The Hill in Autumn". The science comes to life when we can be certain that Tom was looking west while he painted. Thank you!
Inscription recto:
- l.r., estate stamp Inscription verso:
- c., estate stamp;
- u.l., in graphite, AM;
- u.l., in graphite, 8;
- c., in graphite, 6A (or 46A);
- below stamp, label, in graphite, The Hill in Autumn /
- 1914-J and in ink, Dr. James MacCallum National Gallery of Canada, Ottawa
This was another one of those panels that caught the eye of Tom's patron, Jim MacCallum. The good doctor must have made the acquisition when the panel surfaced during the sorting and naming process in the spring of 1918.
Provenance:
- Estate of the artist
- Dr. J.M. MacCallum, Toronto
- National Gallery of Canada, Ottawa. Bequest of Dr. J.M. MacCallum, Toronto, 1944
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| "The Hill in Autumn" as it would have appeared in Tom's pochade box. |
In "The Hill in Autumn", Tom actually captured the swallow shapes of the tilted vortices associated with a local wind maximum in the upper atmosphere - cirrus uncinus. This was a skyscape painting. Paint on Tom!
For those interested in a bit more science, I also wrote about "Curly Hook Cirrus" in "Lines and Swirls Explained". Also in "A Jet Streak with a Paddle" I explained why deformation zones parallel the wind in the entrance region of a local wind maximum. In sharp contrast, the deformation zones are perpendicular to those winds as they decrease downstream from the local wind maximum. These clouds can reveal a lot about the atmosphere. These discussions were a tough sell in the Weather Centre when the pressures of deadlines and workload precluded a more artistic investigation of the "why" behind the clouds.
Warmest regards and keep your paddle in the water,
Phil Chadwick, Tom Thomson Post TT-114
PS: Tom Thomson Was A Weatherman - Summary As of Now contains all of the entries to date.
PSS: Should you wish to have Creative Scene Investigation applied to one of Thomson's works that I have not yet included in this Blog, please let me know. It may already be completed but not yet posted. In any event, I will move your request to the top of the list. If you made it this far, thanks for reading!
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