A Bountiful Flock of Floccus Clouds
March 31, 2021
Photographer: Ray Boren
Summary Author: Ray Boren
On a pleasant day poised between autumn and winter, I strolled out of a favorite bookstore in downtown Bountiful, Utah and happened to glance upward. Directly overhead was a beautiful, cloud-splashed sky. I had parked my car alongside a park-like city block featuring the Bountiful Tabernacle, a Greek Revival meetinghouse built by Mormon pioneers, which seemed an ideal counterpoint to the speckled sky.
These are apparently altocumulus floccus clouds that looked very much like billowy cotton or fleecy puffballs spilling across a blue canvas. In meteorology, the Latin term altocumulus refers to high and heaped, or massed, globular clouds at a medium altitude of about 6,500 to 22,000 feet (1,980-6,700 m) in elevation. Floccus indicates that they resemble tufts of wool.
I wondered if this might be a mackerel sky, so-called for a fish-scale pattern. Seeking a better understanding, I sent the image to the Cloud Appreciation Society with a sheepish query, and a monitor there responded that a mackerel pattern is more accurately associated with similar Altocumulus undulatus clouds, which have a noticeably undulating wave pattern, not obvious here. The World Meteorological Organization’s International Cloud Atlas notes that Altocumulus floccus clouds sometimes form when the base of a larger, crenelated Altocumulus castellans formation dissipates, which is likely what happened on this pretty day. Photo taken Nov. 30, 2020.