Overcast Air, Cloud-Shadows, and Clouds Beneath the Moon
How cloudy air lights the land, cloud-shadows on the earth, greenery of woods, and clouds under the moon.
A run of short sections gives the painter rules for cloudy skies. Wholly cloudy air makes the countryside brighter or darker by the thickness of the clouds, and uniform overcast flattens the difference between the lit and shadowed sides of a body. Leonardo instructs how to cast cloud-shadows on the earth, notes that clouds redden the nearer they are to the horizon, and observes that under interposed clouds the greenery of woods shows only faint shadows driven into the trees' interior. A final section begins on clouds beneath the moon, which are darker than the rest. The page is text only, with no diagrams.
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Overcast air flattens light and shadow on the land
Wholly cloudy air renders the countryside beneath it brighter or darker according to the greater or lesser thickness of the clouds set between the sun and the land. When that thickened air is of uniform thickness, you will see little difference between the illuminated and shadowed parts of any body.
Casting cloud-shadows on the earth
Make the shadows of the clouds upon the earth, with the intervals struck by the solar rays, with greater or lesser splendor according to the greater or lesser transparency of the clouds. Clouds are of greater redness the nearer they are to the horizon, and of lesser redness the more remote.
Greenery of woods under interposed clouds
When clouds come between the sun and the countryside, the greenery of the woods shows shadows of little darkness, with little variety between shadow and light. Illuminated by the great sum of the light of their hemisphere, the shadows are chased and take refuge toward the center of the trees and toward the part of them that faces the earth.
Clouds beneath the moon at night
The cloud found beneath the moon is darker than any of the others, and the more remote clouds are brighter. The part of a cloud that is transparent, within and among its edges, appears brighter than the like part in more remote clouds, because in every degree of distance the middle grows clearer. The passage carries over onto the next folio.