A circumhorizontal arc, commonly called a fire rainbow, appeared over West Virginia in August 2026. This optical phenomenon creates bands of vivid color across the sky without involving precipitation or rainbows in the traditional sense.
Fire rainbows form through a specific alignment of atmospheric ice crystals and sunlight. The effect requires hexagonal ice crystals suspended in cirrus clouds at high altitude, positioned so sunlight enters through one face and exits through a different face. The precise geometry bends and separates wavelengths of light, producing the characteristic spectrum of reds, oranges, yellows, and greens that appear to flame across the sky.
Unlike conventional rainbows, which form when light refracts through water droplets and requires the observer to face away from the sun, circumhorizontal arcs occur only when the sun sits above 58 degrees in the sky. The arc always appears parallel to the horizon, arcing through the sky directly above the sun's position. This geometry explains why fire rainbows remain rare sightings at high latitudes and appear most frequently during summer months when the sun climbs highest.
The West Virginia observation captures the phenomenon in ideal conditions. Clear skies, sufficient ice crystal abundance at the right altitude, and proper solar angle converged to produce the display. NASA's Astronomy Picture of the Day program, which archives daily observations of atmospheric and space phenomena, featured this sighting as an example of Earth's optical physics in action.
Fire rainbows represent accessible demonstrations of atmospheric optics available to ground observers. Unlike eclipses or planetary transits requiring specific preparation or instruments, circumhorizontal arcs demand only attention and favorable weather. The West Virginia capture demonstrates how careful observation of local skies continues yielding documented examples of these short-lived, geometrically precise light shows.