Mammatus Over Boulder Colorado at sunset, this is a southwest scenic landscape view from east boulder county towards the flatirons. If you look on the horizon there is a small bolt of lightning. Mammatus, also known as mammatocumulus, is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. The name mammatus is derived from the Latin mamma. Wikipedia *PLEASE NOTE, WATERMARKS WILL NOT BE ON THE PURCHASE PRINTS*