sunniness

nouns

lightness created by sunlight
sunniness
is a type of (narrower)
the visual effect of illumination on objects or scenes as created in pictures
"he could paint the lightest light and the darkest dark"
light, lightness
the quality of being cheerful and dispelling gloom
"flowers added a note of cheerfulness to the drab room"
cheer, cheerfulness, sunniness, sunshine
is derived from
sunny