This colour study is typical of the hundreds of experimental sketches
that Turner habitually made as part of
his process of painting in watercolour. He used them to test how his paper reacted to his colours, to lay out compositions, and to recreate atmospheric effects. Many were produced in batches, with Turner moving from sheet to sheet as
if he was on a production line.
Turner had always been greatly
interested in the sky but, like his contemporary John Constable, his
interest in making cloud and sky
studies seems to have been especially heightened in the years around 1820.