pannus
PAN-us
Ragged fragments of low cloud clinging to the base of a larger rain cloud — the shredded, dark wisps that hang beneath the storm. Pannus forms when rain saturates the air below the cloud base, creating a secondary condensation layer. It's the signal that rain is imminent or already falling nearby.
Etymology
Latin pannus, a piece of cloth, a rag. The cloud in tatters.
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