This was
your sky.

Rainbow Airglow over the Azores

The sky over the Azores glows like a repeating rainbow due to airglow. Airglow happens all the time, but it's usually faint. A disturbance, like an approaching storm, can create ripples in Earth's atmosphere called gravity waves. These waves make the airglow structure visible, especially in long-exposure photographs taken along the vertical walls of the airglow.