1 / 1

20181026_sha_z03_361 ©NASA/ZUMAPRESS.com/MAXPPP - October 26, 2018 - West Virginia, U.S. - Image Released Today: It's autumn in the Northern Hemisphere, which means many people living in mountainous areas are awakening to fog-filled valleys. As nights lengthen with the season, the atmosphere has more time to cool down and approach the dew point, the temperature at which the air becomes saturated and water vapor condenses into fog. Since cold air is denser than warm air, it sinks and drain into valleys, meaning fog develops there first. VIIRS on the Suomi NPP satellite captured a glimpse of this process at work in the mountains of West Virginia on October 24, 2018.