Altocumulus
Rows and honeycombs of small rounded patches, white with grey shading, at middle height.
What it looks like
Rounded patches, rolls or lumps arranged in rows or a honeycomb, white with grey undersides. Each element is small: hold a finger up at arm's length and it covers one to three fingers. A sky full of them is sometimes called a mackerel sky.
What it means
Moisture at middle levels. On a warm summer morning, altocumulus with little turrets on top hints at thunderstorms later in the day. As a broken layer at sunset it produces the most spectacular colours of any cloud.
Not to be confused with
Stratocumulus, which is lower, greyer and has elements more than three fingers wide, and cirrocumulus, which is higher, has elements smaller than a finger and no shading at all.
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