Cirrocumulus are a relatively rare cloud forming ripples which may resemble honeycomb or the scales of fish, giving rise to the phrase 'mackerel skies'.
Height of base: 20,000 - 40,000 ft
Shape: Layers or patches of cells
Latin: cirrus - lock or tuft of hair; cumulus - heap
Cirrocumulus clouds are made up of lots of small white clouds called cloudlets, which are usually grouped together at high levels. Composed almost entirely from ice crystals, the little cloudlets are regularly spaced, often arranged as ripples in the sky.
Cirrocumulus can sometimes appear to look like the scaly skin of a fish and are sometimes referred to as a "mackerel sky".
Cirrocumulus cloudlets are usually made up of both ice and 'supercooled' water, this means that water remains a liquid, even at temperatures well below 0oC. They form when turbulent vertical currents meet a cirrus layer, creating the puffy cumulus shape.
Cirrocumulus clouds can also form through contrails, the vapour trails left by planes as they fly through a dry upper troposphere. These streaks can spread out and become cirrus, cirrostratus and cirrocumulus.
Precipitation from cirrocumulus clouds never reaches the surface, meaning that these clouds are usually associated with fair-weather. However their appearance can often prelude stormy weather meaning you should make the most of the sun while you still can.
Cirrocumulus clouds have four defined 'species', which describe its appearance;
Last updated: 4 August 2016