A blanket of steam fog covers Lake Superior as powerful polar vortex batters the US midwest, bringing wind chill values to more than 40 degrees below zero in some areas. <br /><br />The ''steam fog'' phenomenon happens when the temperature in bodies of water, like lakes and rivers, is warmer than the air.<br /><br />Time-lapse footage, captured on January 27, shows steam fog gliding across Lake Superior as the sun shines on the horizon in a beautiful winter scene.<br /><br />Lake Superior, the largest of the Great Lakes of North America, is also the world's largest freshwater lake by surface.
