Thick fog blanketed parts of Maryland on Tuesday, December 10, prompting officials to issue advisories.Tim Pruss decided to see just how thick that fog was, and he sent his drone on a vertical flight over 300 feet up, to where a beautiful blue and golden dawn sky greeted his camera.The National Weather Service (NWS) warned that low visibility could make driving conditions hazardous, with visibilities of less than one-fourth of a mile observed in some locations along the Blue Ridge. Credit: Tim Pruss/@MyDrone.Pro via Storyful