accidental light

accidental light (plural accidental lights)

1. (painting) A secondary light; an effect of light other than ordinary daylight, such as the rays of the sun darting through a cloud, or between the leaves of trees; the effect of moonlight, candlelight, or burning bodies.
   • 1819, Abraham Rees, The Cyclopædia:

     Another species of accidental light, is occaſioned by the One thing more should be observed