photo #6550136

We identify the lacunosus variety of clouds not by what’s there but by what is absent. It’s a sky full of holes fringed by clouds, and they can form where a layer of cool air sinks in pockets through warmer air. When moisture content is right, cloud develops where the air rises, with gaps showing where it sinks. It is likely that rounded holes with fringes of cloud become the dominant pattern, rather than rounded clouds fringed with gaps, when the cloud forms in a region of high pressure, which is associated with a general pattern of sinking air. This has the effect of suppressing the vigour of the rising, cloud-forming, currents of warmer air and adding strength to the sinking, gap-forming, pockets of cooler air. Philip Tingey (Cloud Appreciation Society Member 45,142) spotted these Cirrocumulus lacunosus clouds above Chilliwack, British Columbia, Canada, in a sky that resembled the froth and spume of a roiling sea.