Astronaut photograph of Hawaii's Kilauea volcano (left) and volcanic gas wafting westwards from the volcano. Vog, a haze formed when sulphur dioxide from an erupting volcano reacts with oxygen, can be seen being transported downwards of the volcano. This vog forms repeating patterns of swirling vortices known as von Karman vortices. Photographed on the 18th of February 2015.