After a while, the study of clouds seems to represent a type of problem that all artists have. Even if we have never painted a day in our life, we have seen clouds, and perhaps can empathize with the artist. Clouds are transparent. They have minute detail we can barely see. When they are interesting, their elements are extremely slight. They have no pity for the artist—clouds are constantly changing. In the moment it takes to look down and make a mark on the paper, they have shifted in ways that are both perceivable and invisible.

On this painting, American painter Thomas Lindsay has inscribed some notes: “A wonderfully splendid Sunset. The warm clouds were of a Copper color (not thus red) & appeared to float, catching the light most brightly on their lower edges, whilst the clouds below them were of a dirty purple, or dark ash color, but much bluer at the top towards the zenith.” Perhaps he was worried that the image he created didn’t do it justice, and that the words would be more accurate.

The study of clouds can be laborious—a dramatic affair. But it can also be just a few scribbles on a piece of paper, like this one by Antoine Alphones Montfort. If this sketch was anything else besides clouds, you wouldn't think this was something that belonged in a museum. And yet, these white scratch marks are preserved for history in one of the most prestigious museums in the world.