From “Scene Painting and Bulletin Art” (Frank Atkinson, 1916, page 30):
“In the preparation of sky tints, it will be observed that they are graduated in intensity by a greater or less quality of tone…and in laying them in, we place the strongest of them at the highest part of the sky, making them paler or higher in value and less intense as we descend to the horizon, where the use of blue is discontinued and other tints are used, suitable to the character of composition and the mood of the day.”
The image below is from the Scottish Rite theatre in Winona, Minnesota (Sosman & Landis design for the 3rd degee – Seacoast near Joppa). It is currently in a storage unit with the remainder of the scenery collection on the stage.