Marcy Cohen spotted the smooth, disc-like form of an Altocumulus lenticularis cloud over the jagged peaks near Fagurhólsmýri, Iceland. Despite appearing like a stack of plates standing on their ends, the formation will have been arranged like plates stacked on top of each other horizontally. The appearance is largely a trick of Marcy’s wide-angle lens as she looks up towards the base of the layered, disc-like formation.

This distinctive form of the mid-level cloud Altocumulus develops as moist winds blow over mountain terrain and take on a rising-and-dipping motion in the lee of the peaks. The smooth discs known as lenticularis form at the crests of these invisible air flows. When the airflow consists of alternating layers of moister and drier air, the cloud can have a stacked appearance like this. Remember, you’re looking up at it here from below. With this stacked appearance, you could give Marcy’s cloud the full name Altocumulus lenticularis duplicatus – and, you know what, we think we’ll do just that.