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Taking their name from the Latin for ‘having holes’, lacunosus formations have a mesh-like appearance. This cloud variety can form wherever a layer of cold air drifts over one that is distinctly warmer. The cold air, being denser, sinks down through the warmer layer below, its movement arranging itself into a regular pattern of convection cells. The formation’s holes mark the descending pockets of cold air, its cloudy fringes where the warmer air is rising between them and condensing into droplets. Lacunosus is a net for the sky, cast out to catch your attention.Altocumulus lacunosus spotted above Columbus, Ohio, US by Krista Donnelly (Cloud Appreciation Society Member 44,380).