This phenomenon is often informally referred to as a ‘fire rainbow’. Ice crystals in the cirrus cloud are acting as floating prisms and refracting the sunlight. To refract the sunlight in a collective manner like this, the ice crystals must be all be aligned horizontally. Thus, this phenomenon is quite rare to see due to the specific alignment of the crystals. It’s especially rare to capture an image like this when you consider the forces that are constantly acting on clouds within the atmosphere. If the wind were to separate the cloud or re-align the crystals, the same effect would not be achieved. The physics represented in this photo creates a captivating art piece with the vibrant unstructured colors as the focus. The cloud structure resembles flames and creates a more interesting shape than a familiar rainbow. This picture was taken near North Fork Mountain in West Virginia by Christa Harbig.
Photographer: Christa Harbig
Citation: “APOD: 2021 August 30 – a Fire Rainbow over West Virginia.” Astronomy Picture of the Day, NASA, apod.nasa.gov/apod/ap210830.html.