Nacreous clouds usually form in very cold conditions over polar regions and within the stratosphere, far above our normal clouds. One of the highest clouds, they are often referred to as "mother ...

They are actually a rare cloud called nacreous clouds or polar stratospheric clouds, they are also known as mother of pearl due to their iridescent appearance. They occur in the winter polar ...

Because of the height and temperature needed this cloud is also known as polar stratospheric cloud - here's one pictured over Warrenpoint, County Down Rare nacreous clouds have been photographed ...

Following the sweeping path of a cold wave through the Arctic, the skies were alight with rare polar stratospheric ... rare rainbow clouds, more scientifically known as nacreous clouds, only ...