Iridescent Sunset Mammatus

If every there is a Colorado summer sunset that doesn't leave me standing slack-jawed and awestruck, just turn me into Soylent Green. My wonder and joy will be dead. This was sunset in late July 2016. Lower-altitude cumulus clouds are silhouetted, but the trailing edge of large anvil-headed cumulonimbus was lit at low angle by the Sun (which had already set behind the Rocky Mountains from my location). Mammatus clouds were forming; weird bulb-shaped clouds that are common in patches, but also so...