Freezing Fogbow Documented Over Mauna Kea Summit After Winter Storm

A rare atmospheric phenomenon, identified as a freezing fogbow, was documented above the summit of Mauna Kea in Hawaii on January 5, 2026. This optical event materialized in the wake of a substantial winter storm system, specifically classified as a 'Kona low,' which had delivered significant quantities of wet snow to the elevated regions of the Big Island.

The formation mechanism for a freezing fogbow requires a specific confluence of atmospheric conditions: the refraction of sunlight passing through an extremely dense concentration of minute, supercooled water droplets suspended within the fog layer. Unlike a standard rainbow, which results from larger raindrops, the diminutive size of these cloud particles causes the resulting arc to appear predominantly white or muted in color, occasionally displaying a subtle reddish hue along its outermost edge. This spectral characteristic differentiates it from the full-spectrum display of a conventional rainbow.

Meteorological observers on site also indicated the potential presence of characteristics associated with a 'supernumerary fogbow,' suggesting an unusually high uniformity in the size distribution of the cloud droplets present in the fog bank. The essential prerequisite for sustaining the necessary supercooled water particles was the maintenance of subfreezing temperatures consistently above the 10,000-foot elevation mark on Mauna Kea.

Mauna Kea, a dormant shield volcano, is globally recognized for its astronomical observatories and unique microclimates that facilitate rare weather occurrences, often contrasting with tropical conditions at sea level. The Kona low system, typically originating from the southwest, draws moisture from the central Pacific, leading to heavy precipitation when it interacts with the island's high terrain. This observation provides valuable data for atmospheric physicists studying light scattering in mixed-phase clouds, documenting the complex interplay between tropical moisture influx and high-altitude thermal dynamics.