Tom’s motivation to “record” this particular observation –the cloud structure.
This sky pattern that intrigued Tom is also a frequent flyer. I have many examples. The clues to determine the viewing angle are subtle and require being familiar with the cloud patterns.
An educated, plein air guess would be that the artist is looking northward away from the sun. In Tom’s painting this is where we see the westerly cold flow with the clouds growing in size from left to right. The sun was getting low on the western horizon (to the left) and this explains the illumination on the west facing tops of the stratocumulus (SC). There is also some yellow hue in the distant sky that is associated with a setting sun and Rayleigh scattering removing the blue colour from the sky. The flow that Tom painted was cold, unstable and moist with low based turbulent stratocumulus. This painting was done late in the afternoon in which case Tom was certainly looking northerly.
The shapes of the stratocumulus as indicated by the purple dashed arrows indicates the westerly wind direction. The upwind cloud arches are formed by the vector addition of the updraft forming the cloud and the wind itself.