Videos captured on Thursday over Jonggol, West Java, showed swirling bands of pink, green, blue and yellow across thin clouds, prompting viral speculation that the footage was computer‑generated. Atmospheric researchers verified the phenomenon as cloud iridescence, an optical effect produced when sunlight diffracts through uniformly tiny water droplets or ice crystals in thin cloud layers.

The diffraction separates sunlight into its constituent colours, creating pastel patterns that appear close to the Sun. Researchers, including atmospheric optics specialist Joseph A. Shaw, said the Indonesian display required a precise combination of thin, semi‑transparent clouds, stable air, and the correct solar angle for the colours to emerge.

Cloud iridescence is uncommon because it demands that cloud particles be both extremely small and nearly identical in size; even slight variations suppress the effect. The phenomenon is most frequently observed in altocumulus, cirrocumulus, cirrus and lenticular clouds, which often form at high altitudes where conditions remain stable.

Scientists emphasized that the colourful clouds are not rainbows, which result from refraction and reflection inside raindrops, but arise from diffraction and interference. They also noted growing public skepticism toward striking visual media amid the rise of realistic AI‑generated imagery.

Experts will continue to monitor atmospheric conditions for further iridescence events and advise the public that such displays are natural, documented phenomena, not digital fabrications.