Tom Thomson's Evening Cloud Fall 1915

Thomson was inspired by the weather. Artistic compositions full of varying tones and colours are presented hourly with the changing weather - and the paintings literally come to you! One does not need to travel to the south of France to be energized. I have been blessed with the same situation during the past four years of COVID. Nature and specifically the weather can be everything that you need to find a purpose in life. 

"Evening Cloud" from the fall of 1915 is an exuberant example of Tom at his best. The low horizon characterizes his skyscapes with the clouds as the star attraction. 

Evening Cloud
Alternate titles: Evening Clouds; Storm Cloud; Storm Clouds Fall 1915
Oil on composite wood-pulp board 8 9/16 x 10 9/16 in. (21.7 x 26.8 cm) 
Tom's Paint Box Size, Catalogue Number 1915.76

Tom included all the clues we needed to fully understand the weather that autumn evening. I asked my colleague Johnny Lade to have a look at this painting as if he was making a weather observation. Known to his students as "Johnny Met", he has a lifetime of experience observing the actual weather. Johnny nailed this observation since Thomson painted exactly what he saw.

"This painting looks like the true atmosphere The main cloud mass is a towering cumulus in a dissipating stage. The tops are still in the sunshine maybe at the 20,000 range. The grey bottoms are blocked from the sunshine by the tops. The clouds are moving away from the painter and the bottoms might indicate a passing showers. The dark horizon indicates showers as a cold front moves away leaving a fresher brand of air. The wind behind the front is stirring up the lake and the sun is reflecting off the waves."

Johnny's observation rings true and will be further explained in the following graphics.  

The towering cumulus was front-lit. The sun was on Tom's back and his right shoulder.  The distant shore was in shadow (dark tone) and lacked colour. The sun had set at least at the lowest levels of Tom's vista.

The cumulus congestus cloud was still vigorous but starting to dissipate with the setting sun. The cold front that Johnny mentioned provided the trigger to initiate that convection but a significant portion of the convective available potential energy (CAPE) was still provided by the sun. The bright faces of the towering cumulus turned toward the setting sun lacked the cauliflower texture of a robust, convective bubble. 

Rayleigh scattering removes the shorter wavelengths from the direct beam of the setting sun. The original white light of the sun becomes increasingly orange and then red as it passes through an ever-increasing atmospheric path until the sun sinks below the western horizon. 

The following graphic (made to explain another painting) summarizes the effect of Rayleigh scattering on the colour of the light remaining to illuminate the scene. Increasing amounts of particulates within the planetary boundary level during the day can scatter all but the longest wavelengths from the visible spectrum - only red light remains in some sunsets. Red sunrises are rare and more likely to be yellow or orange. 

Tom observed the dark cumulus congestus cloud base as purple! As Johnny noted, the direct beam from the setting sun was no longer reaching that portion of the cloud. The cloud was optically thick and no light was getting to the cloud base through that towering cumulus. Blue light from Rayleigh scattering could reach the cloud base. Red sunset light forward scattered by large particles (Mie scattering) in the lowest levels of the atmosphere combined with the blue to result in the purple that Tom painted. 

The large convective raindrops that comprise the shower under the towering cumulus were painted distinctly grey! Tom had to mix some burnt or raw umber with his oils to record that colour. Matching that distinct colour had to be a very deliberate act! The larger raindrops can only Mie scatter any incident light in a forward direction. The setting sun only provided minimal red light at that low elevation and an even smaller amount of that could be returned to Tom's eye. Minimal light passed through the optically thick cloud. The colour of the shower had to be darker and lacking in colour. Tom painted what he saw. 

There is another factor to consider when explaining the purples and pinks that Tom observed! Tom was also possibly looking at the eclipse of the atmosphere by the shadow of the earth - the Belt of Venus (associated with the Greek goddess Aphrodite and Roman goddess Venus - not the second planet in the Solar System). The Belt of Venus is not an available option for any back-lit illumination. 

The earth casts a shadow on the lower atmosphere twice a day at your location: the first at sunrise if you gaze toward the west and the other at sunset looking toward the east. The shadow in the sky lasts only about 15 minutes - just long enough to boldly observe and lay the oils on a sketch. This “Belt Of Venus” phenomenon helps to explain the even pinker colours of the towering cumulus on the eastern horizon. 

The following graphic to explain this phenomenon must be greatly distorted.  

• Remember that the atmosphere is actually quite thin similar to the skin of an apple. The troposphere where almost all weather occurs extends only 8 to 14.5 kilometers high (5 to 9 miles). This part of the atmosphere is dense and thus the most likely to scatter light creating the visual effects that we enjoy. 
• Also, recall that the sun is far from the earth at about 8.3 light-minutes away. On average, the earth is 150 million kilometers away from the sun.
• The earth is only 12,742 km in diameter. The dimensions of the earth are dwarfed by the distances involved. 

The Belt of Venus (also called Venus's Girdle or the anti-twilight arch) is an atmospheric phenomenon visible shortly before the sun rises or after sunset, during civil twilight (the geometric center of the sun is within 6 degrees below the horizon). The pinkish glow surrounds the observer and extends 10 to 20 degrees above the horizon.

An artist can't chase the fleeting colours of light while painting en plein air. Nature and especially the weather change so fast that one must decide when to lock in the colours and composition and ignore what changes might occur after that. My advice to students was to first paint what was changing the fastest - "lay the oils in and leave them alone - move on". Remember that light moves at 186,000 mi/sec or 3 followed by eight zeroes meters per second. That is fast! Students to tried to chase the light usually ended up painting "mud". Thomson's strength was "to observe, lay it in, and never touch it agin."

The study of light and its interactions with particles in the atmosphere can fill several textbooks. Happily, artists can stay scientifically accurate if they just paint what they see. Tom did just that!

The gravity waves in the altocumulus clouds at the top of the panel indicated that the winds were southerly at that elevated level. The wavelength of those gravity waves can even be used to estimate the wind speed - something I did when I was an operational meteorologist. I do not do that anymore and you do not need to. 

All of the above allows us to place Thomson within the weather patterns of that autumn evening. The cold front was passing Tom's location as the warm sector of the weather system receded to the east. 

Significant wave action but with minimal white caps suggested that the winds were Beaufort Scale Gentle Breeze of 7 to 10 knots producing "large wavelets, crests begin to break, scattered whitecaps". The surface winds had been blowing from right to left (from the south) but with the passage of the cold front, the winds would have started to veer to the west. The shore on which Thomson was standing would have significantly reduced the fetch of the wind over the lake justifying a higher wind speed estimate based solely on the Beaufort scale.

The nondescript distant shoreline location could be anywhere... and probably no one knows.

The oils were smeared along the left and right 
edges of the panel when Tom placed and later
removed the art from his paint box. 

Inscription recto: 

• l.r., estate stamp 

Inscription verso: 

• c., estate stamp; 
• u.c., in pink graphite or pastel, 28; 
• u.l., in graphite, (undistinguishable) / Tom Thomson / p..d / 35OO ; 
• u.l., in graphite, le… (crossed out); 
• u.l., in graphite, RWL (crossed out); 
• u.l., in graphite, …(crossed out); 
• u.l., in graphite, S..nset; 
• u.c., in red pencil, Laidlaw; 
• u.r., in graphite, fall 1915 2?; 
• u.r., in red pencil (circled), 16; 
• l.r., in green graphite or pastel, B or 13; 
• l.r., Gift to R.W.L.L./R.a. Laidlaw; 
• l.r., in green graphite or pastel, B or 13; 
• l.c., in graphite, 14. M. Thomson (crossed out); 
• l.c., in graphite, 8; l.l., in graphite, J & ???t / Studio Bldg / To; 
• u.l., label, in red pencil, Gift to R.W.L. Laidlaw / R.A. Laidlaw; 
• u.r., label, in red pencil, T 45 Thomson Collection @ Art Gallery of Ontario 

Provenance 

• Estate of the artist 
• Elizabeth Thomson Harkness, Annan and Owen Sound 
• W.A. Laidlaw, Toronto 
• R.A. Laidlaw, Toronto, 
• after 1959 R.W.L. Laidlaw, Toronto and King City, 
• by descent Ken and Brenda MacDonald, Winnipeg 
• David Loch, Toronto 
• Private collection, Toronto 
• Thomson Collection @ Art Gallery of Ontario

This is another one of those panels from the stack of Thomson's paintings retrieved from the Shack. In the spring of 1918 Lawren Harris and J.E.H. MacDonald had a virtually impossible task to sort through The application of the Estate Stamp on "Evening Cloud" did not cause much damage to the lower right of the panel. 

This graphic also highlights the wave action lacking in white caps. 

The alternate titles for "Evening Cloud": Evening Clouds; Storm Cloud; Storm Clouds suggested by Harris and MacDonald missed the mark. The cold front had passed and fair weather was on the way overnight. The westerly or northwesterly winds would diminish. The pressure was rising, The following day would be a great day for more pein air painting of the autumn colours. 

This painting went to Thomson’s eldest sister upon his passing. Elizabeth's husband was Thomas “Tom” J. Harkness who was appointed by the Thomson family to look after the affairs of Tom’s estate. T. J. and Elizabeth lived in Annan, Ontario, just east of Owen Sound. From Elizabeth, aka "Mrs. Harkness", the painting went to the Laidlaw family who were avid collectors of Thomson's art (as encouraged by Harris). Eventually, the painting went to the  Art Gallery of Ontario where I first saw it - nose to nose. 

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. 

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 needs to be posted. In any event, I will move your request to the top of the list. If you made it this far, thanks for reading! There is a lot of science in this small panel and I wanted to cover most of it...