A study of cloud effects: three layers of strata nebulae and a cumulus. Below is what may be a dark cumulus, or the top of mountain peaks. There is a note on clouds along the centre at the top. The sheet is very much rubbed. It may well have been joined to another originally. Melzi's number 135.

Leonardo’s technique of red chalk on red prepared paper reached its logical conclusion, at the end of his life, in a small group of sheets executed in black chalk (or possibly charcoal) on paper rubbed all over with the same medium, or prepared with a dark grey coating; one bears the date 24 June 1518, the latest date written by Leonardo in any of his notes. The rubbing-in of the chalk made the surface of the paper smoother and the drawing more vulnerable to abrasion, and Leonardo’s study here has been largely effaced. But three layers of stratiform clouds can be discerned in the upper half of the sheet, and two formations of cumuliform clouds to centre and lower left, possibly with mountain peaks below. The note reads ‘The shadows in clouds are lighter in proportion as they are nearer to the horizon.’

Text adapted from Leonardo da Vinci: A life in drawing, London, 2018