Cirrocumulus is a high level cloud that can form patches, layers or sheets without any shading, composed of very small elements in the form of grains or ripples. The elements are less than less than 1o width, about one or two fingers width with arm extended vertically.
In many ways, these clouds look exactly the same as Altocumulus stratiformis, but the individual cloudlets are much smaller, only 1o in width, and they are entirely white without any obvious shading. On this photograph the smaller size of the cloudlets is not obvious as a zoom lens was used.
Each cloudlet has very little vertical growth, and they appear as a broken sheet.
Cirrocumulus stratiformis, Wolstanton, Staffordshire
11th November 2017
© Paul Swinhoe
The smaller cloudlets and flattened layer-like pattern of these clouds is seen more clearly here, but there is one apparent irregularity - parts of these clouds appear grey.
However, this shading is not caused by any depth within the cloudlets themselves. They are simply so thin that the fail to generate the strong white reflection, of the thicker clouds nearby.
Cirrocumulus stratiformis, May Bank, Staffordshire
8th August 2018
© Paul Swinhoe
The photograph shows several different types of cirrus cloud, but those with a trail of precipitation falling sub-vertically, wisping away to the left, are Cirrocumulus floccus. They occur when the cloud is thick enough for larger ice crystals or fine snow to develop. As this falls towards the surface, the air beneath is suffiently dry to encourage sublimation to occur.
Towards the left of the image there is a case where the amount of lateral movement is much greater, and the falling precipitation has been swept almost horizontally to the left, forming the comma shape typical of Cirrus uncinus.
Beneath both, even though it might look initially as though it is on the same level, is a layer of Altocumulus stratiformis translucidus.
Cirrocumulus floccus, Wolstanton, Staffordshire
13th July 2002
© Paul Swinhoe
Cirrocumulus is normally considered a high level cloud, but at times when the tropopause is much lower, when a cold air mass has travelled south from polar regions, the cloud can occur quite low down. In this case, the cloud is particularly thick and shows pendant mamma on its lower edge. These are downward bulges which are caused by the weight of ice crystals, but they are still not big and heavy enough to break free and start falling to the surface as in the case of Cirrocumulus floccus.
The low evening sunshine on the cloud creates quite a drammatic effect and highlights its fibrous upper regions as well as the mamma.
Cirrocumulus with mamma, Harriseahead, Staffordshire
4th September 2012
© Lionel Burch
These high clouds have the small elements or cloudlets of Cirrocumulus but also show an undulating pattern. They indicate wave action at the levels of the clouds, running at 90o to the length of the rolls of cloud. Where the air is ascending and cooling the clouds form, and where it is descending and warming up, the clouds evaporate, producing lines of blue sky between the roles of cloud.
Cirrocumulus undulatus, Tittesworth, Staffordshire
8th August 2018
© Paul Swinhoe
The central part of this photograph also shows Cirrocumulus undulatus, but this time looking head on, which makes it a little more difficult to identify.
Towards the left there is a layer of Cirrocumulus stratiformis present at a slightly lower altitude.
Cirrocumulus undulatus, Tittesworth, Staffordshire
8th August 2018
© Paul Swinhoe