For almost forty years, Williams has been making oil sketches of skies to use as reference for the backgrounds of larger works. Through this process, he developed an interest in the ephemeral characteristics of the sky as a primary subject rather than one that is subservient to another work. Williams describes his approach:"The pace of making a cloud study is dictated by the behaviour of the sky. Time is often limited and so working on small panels enables me to stay true to what I’m seeing, no matter how fleeting. The challenge is always how to note the trajectory of a cloud, or a subtle change in light, while still keeping the essence of the moment that nature is presenting."