Photos

This cloud formation was observed in the midle day of 23th eptember in the "Purace" National Natural Park.

Mammatus (also known as mammatocumulus, meaning "bumpy clouds") is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. The name "mammatus" is derived from the Latin mamma (breast), due to the resemblance between the shape of these clouds and human female breasts.
Mammatus are most often associated with the anvil cloud that extends from a cumulonimbus, but may also be found under altocumulus, altostratus, stratocumulus, and cirrus clouds, as well as contrails and volcanic ash clouds.
Mammatus may appear as smooth, ragged or lumpy lobes and may be opaque or semitransparent. Because mammatus occur as a grouping of lobes, the way they clump together can vary from an isolated cluster to a field of mamma that spread over hundreds of kilometers to being organized along a line, and may be composed of unequal- or similarly-sized lobes. The individual mammatus lobe average diameters of 1-3 km and lengths on average of 0.5 km. A lobe can last an average of 10 minutes, but a whole cluster of mamma can range from 15 minutes to a few hours. Their composition is usually mostly ice, but can be a mixture of ice and liquid water or almost entirely liquid water. FROM: Wikipedia