View: https://www.youtube.com/shorts/URVm1kv5-Fc
Credit to that skier, Lenka Lanci, who filmed this in Rakousko Austria earlier this year. The phenomenon is called subsun.
The subsun phenomenon appears when a region of hexagonal ice crystals act as a large mirror, creating a virtual image of the Sun below the horizon. As they fall through the air, the ice forms plate crystals which orient horizontally, i.e., with their hexagonal surfaces parallel to the Earth's surface. When they are disturbed by turbulence, the plates "wobble", causing their surfaces to deviate some degrees from the ideal horizontal orientation, and causing the reflection (i.e., the subsun) to become elongated vertically.
