I shared this picture on Facebook from Meteorologist Brian James, of KVII-TV in Amarillo, TX, and it has created tons of “Likes” and “Retweets” on social media. Some people called it a “chemtrail”, others called it a “shelf cloud”. Actually, it is known as a “Roll Cloud”
As defined in most meteorology books, here is how a “roll cloud” forms: cool air sinking air from a storm cloud’s downdraft spreads out across the surface with the leading edge called a gust front. This outflow undercuts warm air being drawn into the storm’s updraft. As the cool air lifts the warm moist air water condenses creating cloud, which often rolls with the different winds above and below.