title: Ratio of blue to red light: a brief increase following sunset.
abstract: Visible spectra of solar radiation were recorded during sunset. With the development of twilight, there was an expected decrease in the blue-to-red ratio; but directly upon setting of the sun there was a sharp rise in this ratio (due to the predominance of sky-light) which attenuated rapidly to follow the pattern that it had previously taken.
authors.forename: T B
authors.initials: TB
authors.lastname: Johnson
authors.forename: F B
authors.initials: FB
authors.lastname: Salisbury
authors.forename: G I
authors.initials: GI
authors.lastname: Connor