Two views of altocumulus

This view is looking southeast at a dramatic looking patch of altocumulus clouds. The clouds were distinct, partly because the light from the Sun, which was shining on the base of the cloud deck. This reveals individual cloud elements that look like pillows. The “pillows” are cells of upward motion where moisture is condensing as water droplets, even though temperatures are below freezing. The droplets are called supercooled.

Photo Copyrighted by Craig Johnson, 2-16-2019

Look what happened later. The clouds still exhibit cumulus characteristics, which are puffy cloud elements, but the elements are not as distinct as the clouds begin to look more like stratus (layered) clouds. The Sun has climbed high enough in the sky that it is shining on the cloud tops. The upward motion has been weakening so the clouds are turning into a more consistent layer than one with individual cloud elements. While the clouds in the upper photo are called altocumulus, which means high cumulus the cloud type below is called altocumulus stratiformis. The cloud is becoming increasingly more like a stratus cloud.

Photo copyright by Craig Johnson, 2-16-2019