While visiting Big Sur on the coast of Central California, US, Renate Chestnut (Member 59,040) noticed that the sky ‘looked like a beautiful abstract painting with many different brushstrokes’. The celestial brushwork was courtesy of the high ice-crystal cloud Cirrus brushed by the winds of the upper troposphere. Let’s take a look at the strokes that Renate spotted.

The Cirrus clouds appear in separate layers, a form known as Cirrus duplicatus, each of which adds a different texture. The long streaks are the forms Cirrus fibratus, where they’re straight, and Cirrus uncinus, where they have curved ends – known as ‘mare’s tails’. The speckled Cirrus that resemble quick dabs of a brush in the middle and to the left edge of Renate’s sky are the floccus species of Cirrus. Their name means a ‘tuft of wool’ in Latin, and they suggest the high air is unstable and turbulent. The more opaque watercolour washes of cloud at the bottom and top right are Cirrus spissatus, meaning ‘thickened’.

In the words of the nineteenth-century American clergyman and social reformer Henry Ward Beecher, ‘The sky is a vast, ever-changing picture-gallery,’ where everyone ‘may have a masterpiece for the looking.’