... A Roll Cloud Over Missouri . ... A roll cloud . These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form. ... Pictured above , a roll cloud extends far into the distance in the summer of 2005 above Albany , Missouri , USA . ... Publications with keywords: clouds . ...