The grandeur and effortless serenity of clouds never ceases to bowl me over. Their peculiar fusion of levity and shapely definition renders them somehow existentially assuring. Clouds have stirred poets to write magnificent love letters to the skies and psychologists to assure us that cloudy days help us think more clearly. But for of all their psychological rewards, clouds are also a pertinent practical matter in the human conquest of the atmosphere.

In 1966, a century and a half after a young scientist classified the clouds and enchanted Goethe with his system, the U.S. Army made a surprisingly poetic animated film intended to help pilots identify the clouds and their symbols by outlining the ten basic cloud types and their distinct shapes, shades, and altitudes.

Complement with the science of how clouds stay up in the sky, poet Mark Strand and painter Wendy Mark’s astonishingly beautiful homage to the clouds, and Goethe’s science-inspired cloud poems.