When the Sky Turned Iridescent: Seeing Stratospheric Clouds

One evening, just as the sun began to set, we stepped outside to stretch our legs. That’s when we noticed the sky—not dark, not quite light, but glowing. High above us, delicate, shimmering clouds floated in surreal shades of pink, green, and violet. It didn’t look real.

We’d stumbled upon polar stratospheric clouds, also known as nacreous clouds—and they are extremely rare.

These clouds form high up in the stratosphere (about 15–25 km above Earth) and only under very cold conditions, typically below -78°C. They’re most often seen during polar winters in places like Norway, Sweden, and Antarctica, which is why spotting them is such a rare treat.

What makes them so spectacular is how they diffract sunlight. Long after the sun has dipped below the horizon, these clouds catch and scatter the remaining light in pearl-like, iridescent hues—hence their nickname, “mother-of-pearl clouds.”

We stood there in silence, necks craned, completely mesmerised. We’ve been lucky enough to see the northern lights in three different countries—but this was something else entirely. This sky felt delicate, cosmic, almost surreal—like a celestial painting made just for us.

Did You Know? Polar Stratospheric Clouds (Nacreous Clouds)

• Also called: Mother-of-Pearl Clouds due to their soft, iridescent appearance.

• Altitude: They form between 15–25 km above Earth, much higher than regular clouds.

• Temperature needed: Below -78°C! They only appear in extremely cold polar regions.

• Where to see them: Most often in the Arctic (Norway, Sweden, Iceland) and Antarctica.

• Why they glow: They diffract sunlight even after sunset—creating shimmering colours just like oil on water.