Guizhou, China – A rare, near complete circular rainbow has appeared beneath the Huajiang Grand Canyon Bridge in Guizhou Province, China, drawing widespread attention across social platforms after footage of the phenomenon began circulating in the final week of August. The bridge, which opened to traffic on September 28, 2025, holds the record as the world’s highest, with its deck suspended roughly 625 meters (2,051 feet) above the Beipan River. During construction, engineering crews encountered natural karst groundwater beneath the gorge and, rather than diverting it away entirely, redirected the flow into a reservoir system that now feeds a controllable artificial water curtain spanning approximately 300 meters across the canyon. The feature was designed to serve irrigation, tourism, and visual spectacle purposes simultaneously, and operators can adjust its height and flow on demand.
What Conditions Allowed the Rainbow to Form a Full Circle?
Rainbows are produced when sunlight enters a water droplet, reflects once off the droplet’s interior surface, and exits at a bent angle, splitting white light into its component colors. Because this refraction and reflection occurs at a consistent angle near 42 degrees from the point directly opposite the sun, the visible rainbow traces a circle centered on that “antisolar point.” From ground level, the horizon typically cuts off the lower half of that circle, leaving only the familiar arc. Height changes that geometry. Observers positioned high above a dense field of fine droplets, such as mist thrown from a waterfall, can look downward into the spray with no horizon in the way, allowing the full 360 degree ring to become visible at once.
Why Did the Water Curtain Produce This Effect?
The Huajiang water curtain’s design plays directly into these optical requirements. Falling from a height comparable to a 200 story structure, the water breaks into fine mist well before reaching the canyon floor, generating the dense, uniform droplet field needed for a bright, continuous circular band of color. Positioned above the falling water, cameras and onlookers on the bridge deck or nearby viewing platforms gain the elevated vantage point that ground level rainbow watchers rarely get. Favorable sun angle and clear afternoon skies in late August aligned with an active water curtain show, producing conditions engineers and tourism officials in the region had anticipated but not always achieved on camera.
Is the Footage Genuine?
Multiple clips matching the same scene, bridge structure, and surrounding landscape circulated across Chinese state broadcasters, video marketplaces, and short video platforms within days of each other, with on screen text in several versions referencing the location and basic refraction principles. The consistency of structural details, vehicle traffic, and lighting across independently sourced footage supports the authenticity of the event, and it follows a pattern of similar, though less complete, rainbow sightings recorded at the site since its 2025 testing phase.
Has This Happened Before at the Bridge?
Rainbow effects tied to the water curtain are not entirely new; partial arcs have been documented during earlier test runs and public shows following the bridge’s opening. The late August footage stands out for capturing a fuller, more clearly circular formation, a combination tourism authorities in Guizhou’s Bouyei Miao Autonomous Prefecture are likely to highlight as the region continues promoting the bridge as both an engineering landmark and a scenic attraction.
Watch the full circular rainbow form in the mist:
