Constable’s oil studies of skies show a remarkable understanding of the structure and movement of clouds. Most also give a good impression of their three-dimensional volume. This is one of only four examples he painted on a larger format. I researched and discovered that the larger the scale the more difficult Constable found it to balance crispness of detail with speed of execution. This is why the larger cloud studies tend to be more generalised. The inscriptions on the back - ’11 o‘clock’ and ‘Noon’ - indicate that this study took him about an hour to paint.This painting is a strictly observational study of clouds done from the vantage point of Hampstead hill. Within its clumps of clouds you can almost discern an arrangement of straight lines, diagonals and parallels. Yet the whole effect remains subliminal. The sense of depth gives an illusion of peering upwards. A shape can be detected but it is sufficiently diffuse, on the verge of unforming, to keep you uncertain. The structure is so elusive that it might have arrived with no deliberate shaping. Constable became a master at painting clouds because he used optical aids to make his drawings more accurate, according to the artist David Hockney.Hockney believes the use of devices, including lenses, drawing frames and mirrors, was a widespread practice among artists dating back to the Renaissance. The artist, who recently exhibited a series of paintings at the National Gallery's Millennium show which were based on the use of a camera lucida, was responding to claims that landscape artists before Constable were unable to paint clouds.What occurred to me when I read about it was that artists generally made up clouds," Hockney added from his studio in Kensington, west London. "Constable probably did not, however. We have found out that Constable did use a few devices, drawing frames and so on. By 1820, they were certainly rather commonly used by artists. Using a lens does not necessarily diminish the work, but the use itself is still a bit unknown.According to Hockney, Constable might have used a technique which involved tracing the outline of the subject using a concave reflector, which can be found on shaving mirrors. Researching and discovering this has made me also want to try a similar technique. Using mirrors in order to achieve a more accurate, realistic approach to painting clouds. This oil on paper on board painting is extremely helpful with my own studies as I too am focusing on clouds. The natural use of tonal shadowing and highlighting for the clouds form and structure is something I am trying to use in my own work.