Bright colorful clouds shine in the evening sky over Mount Jökultindur in Iceland on January 25.
Nationalgeographic.co.id—A stunning new photo shows the appearance of a very rare rainbow cloud. The clouds emit bright, colorful lights like auroras at various locations in the North Pole, illuminating the Arctic circle.
But what actually causes the appearance of rainbow clouds?
The dark sky of the Arctic Circle glows with subtle multicolored lights. But this jaw-dropping spectacle wasn’t caused by the aurora.
Instead, colorful rainbows are caused by clouds of tiny ice crystals that float higher in the atmosphere than usual.
The clouds, known as polar stratospheric clouds (PSC), only form when the lower stratosphere reaches temperatures below minus 114 degrees Fahrenheit (minus 81 degrees Celsius).
Normally, clouds don’t form in the stratosphere because it’s too dry, but at these very low temperatures “water molecules that are very far apart begin to coalesce into tiny ice crystals that form into clouds,” wrote the report reported by Live Science.
This means PSCs can form much higher than normal clouds, between 9.3 and 15.5 miles (15 to 25 kilometers) above the ground.
As sunlight shines through this crystal cloud, it is scattered, creating many different wavelengths of light, which has inspired the PSC’s nickname, “rainbow cloud”.
Due to the extreme height of the clouds, sunlight can hit the crystals and scatter over the observer even when the sun is off the horizon, which is when these clouds appear brightest.
PSC shines through a gap in the clouds over Kvaløya in Norway on January 25.
In late January, extreme freezing conditions in the stratosphere made it possible for a rare outbreak of PSC in the Arctic Circle, including Iceland, Norway and Finland.
Amateur photographer Jónína Guðrún Óskarsdóttir captured this stunning shot of clear clouds over the top of Mount Jökultindur in Iceland and photographer Fredrik Broms, he took a series of shots of colorful lights over Kvaløya near Tromsø in Norway.
