Planetary polar storms are the norm rather than exception. Earth has one over Antarctica. Saturn has two but the storm at the north pole is strangely shaped like a regular hexagon. The best thinking is that it is a standing wave caused by differing wind speeds on either side of the hexagon. The gradient is perfect to create a hexagon. The same effect was created in the laboratory along with a number of other regular polygons depending on the size of the gradient.
—David Foss