Cirro-velum refers to a specific type of cloud formation that occurs at high altitudes. This type of cloud is typically thin and wispy, and it is often associated with fair weather. Synonyms for cirro-velum include cirrus clouds or thin, high-altitude clouds. These clouds are formed through the condensation of water vapor in the upper atmosphere, and they often appear as patches or streaks of white against a blue sky. Other synonyms for cirro-velum might include "feathery" clouds or "wispy" clouds, as these descriptions accurately reflect the appearance of cirro-velum clouds in the sky.