Rare ‘fire rainbow’ lights up skies over New Zealand’s Nelson region

Residents in the Nelson Region were treated to a breathtaking natural spectacle this week as a rare “fire rainbow” effect illuminated high-level clouds in shimmering shades of pink, green, and gold. The striking display quickly drew attention from locals, many of whom captured and shared images of the glowing sky across social media.

However, meteorologists clarified that the phenomenon was not technically a rainbow. Instead, it was a rare optical effect known as cloud iridescence.

Cloud iridescence occurs when sunlight interacts with tiny ice crystals or water droplets in thin, high-altitude clouds. As the light passes through these particles, it scatters and diffracts, separating into vivid pastel hues.

Unlike a traditional rainbow, which forms due to the refraction and reflection of light in raindrops, iridescent clouds depend on very specific atmospheric conditions. The cloud layer must be thin, and the particles within it must be nearly uniform in size for the colors to appear clearly.

Because the required conditions are so precise, cloud iridescence is relatively uncommon and often short-lived. The colors can fade within minutes as cloud thickness changes or the angle of sunlight shifts. While often referred to as a “fire rainbow” due to its flame-like streaks of color, the event is scientifically distinct from a true rainbow, making the Nelson display both rare and extraordinary.

For many residents, the luminous sky served as a vivid reminder of the beauty hidden within everyday weather patterns.