Why mountains look bluer in summer than in winter
Leafless winter trees turn landscapes gray, while clouded mountains take on the blue of bright air
This page (chapters 800 and 801, with a cross-reference to Book B, folio 19) tells the painter not to depict winter mountains as blue as summer ones. Among distant mountains the darker one shows bluer; in winter the trees, stripped of their leaves, look grayish rather than the darker green of summer foliage, and the greener, darker mass of summer therefore reads as bluer. The final chapter adds that mountains shadowed by clouds partake of blue when the surrounding weather is clear, because the sunlit air is very bright and the mountain's shadowed darkness is seen through it. The whole page is text, in the clean hand of Melzi's compilation.
On this page
Chapter 800: do not paint winter mountains as blue as summer ones
Landscapes made as winter scenes must not show their mountains blue, as summer mountains are seen; among distant mountains the one darker in itself shows the bluer color. The chapter cites Book B, folio 19, and the fourth and fifth propositions of this book.
Leafless trees look gray while green foliage reads bluer at a distance
Since the plants are stripped of their leaves, they show a grayish (tawny) color; but the leaves are green, and as much as green is darker than gray, so much bluer will the green appear at a distance. The shadows of leaf-clad plants are darker than those of leafless ones, in proportion as the foliage is less sparse.
Chapter 801: mountains shadowed by clouds partake of blue
Mountains shadowed by clouds partake of blue when the weather is clear around the cloud, because the air lit by the sun is of great brightness and the shadowed darkness of the mountain is seen passing through that bright air.