Embossed Sky

A very textured-looking north sky is shown looking over 74th Street NE from C Avenue in Cedar Rapids, Iowa around 9:25 AM, Sunday, July 1, 2012. The cloud formation is known as altocumulus undulatus (mackerel sky). The patterns in the formation resemble the scales on a mackerel fish, thus, the name. Altocumulus is an indicator of moisture and instability at mid levels of altitude (8,000-20,000 feet). If the lower atmosphere is stable and no moist air moves in, the weather will most likely remain dry, which in fact occurred here. This patch of altocumulus moved off within 20 minutes or so of the photograph, leaving a brilliantly clear blue sky in its place.