stratospheric clouds
Sky watchers around the Arctic Circle are reporting an outbreak of rare Polar Stratospheric Clouds--super-colorful clouds that sometimes form in the ozone layer above the North Pole. Almost simultaneously, NASA's AIM spacecraft is seeing electric-blue noctilucent clouds floating over the South Pole. The simultaneous apparition of these strange clouds, poles apart, may be a complete coincidence--or not.

Source: Space Weather