This is a phenomenon that occurs during the polar winter in which stratospheric air moves in a circular motion, with a volume of relatively still air in its center. The temperature in the vortex is approximately -130 degrees F (-80 degrees C), which assists in the formation of polar stratospheric clouds. Though usually more prolonged and colder over Antarctica, the Arctic polar vortex does form to a degree, and when the temperatures there are coldest and the vortex persists, Arctic stratospheric ozone destruction on Arctic polar stratospheric clouds has also been observed.