A Withdrawing Thunderstorm at Sundown

What form of cloud is that? This withdrawing cumulonimbus cloud, more most incessantly known as a thundercloud, is considerably irregular as it incorporates the irregular bumpiness of a mammatus cloud on the come ruin, whereas simultaneously producing falling rain on the a ways ruin. Taken in mid-2013 in southern Alberta, Canada, the cloud is transferring to the east, into the gap, because the solar sets in the west, at the relieve of the camera. Within the featured image, graphic sunset colours defective the sky to present the already photogenic cloud striking orange and crimson hues. A darkening blue sky covers the background. Extra in the gap, a rising, waxing, gibbous moon is seen on the a ways suited.