This phenomenon is similar to that of corona, commonly known as glory and is called Brocken Ring. This is a common phenomenon when the observer is located at a high point such as the top of a mountain or the edge of a canyon. When the light source is located directly behind the observer and there is a cloud with small water droplets at a low position relative to the observer, the light is reflected on the cloud and fog. After the small water droplets in the middle are diffracted, the diffracted light is reflected to the observer's eyes, so that they can see the optical image with the observer's shadow as the center and surrounding the colored halo.