Analysis : Mammatus Clouds
Posted July 3, 2011on:
Mammatus, also known as mammatocumulus (meaning “mammary cloud” or “breast cloud”), is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud. The name mammatus, derived from the Latin mamma (meaning “udder” or “breast”), refers to a resemblance between the characteristic shape of these clouds and the breast of a woman.
Mammatus are most often associated with the anvil cloud and also severe thunderstorms. They often extend from the base of a cumulonimbus, but may also be found under altocumulus, altostratus, stratocumulus, and cirrus clouds, as well as volcanic ash clouds.In the United States, sky gazers may be most familiar with the very distinct and more common cumulonimbus mammatus. When occurring in cumulonimbus, mammatus are often indicative of a particularly strong storm or maybe even a tornadic storm. Due to the intensely sheared environment in which mammatus form, aviators are strongly cautioned to avoid cumulonimbus with mammatus.
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. They usually are composed of ice, but also can be a mixture of ice and liquid water or be composed of almost entirely liquid water.
Mammatus clouds are also known as mammatocumulus clouds and are a cellular pattern of pouches hanging underneath the base of a cloud. The name of the clouds refers to the fact that they resemble the breasts of a woman.
Mammatus clouds may be smooth or have ragged, lumpy lobes. These clouds can be opaque or semitransparent. Mammatus occur as a grouping of lobes, so the way they clump together can vary. Some can be an isolated cluster or a field of mammatus can spread over hundreds of kilometers. They can be organized in a line or a jagged slash across the sky composed of unequal or similarly-sized lobes. The average diameter of a lobe is 1–3km. A lobe usually lasts about10 minutes, but a cluster can remain up to a few hours. They usually are composed of ice, but can be a mixture of ice and liquid water or be composed entirely liquid water.
Mammatus clouds are associated with the anvil clouds that extend from a cumulonimbus most frequently, but they can be found under many other types of clouds and volcanic ash clouds. When these clouds occur with cumulonimbus, they are generally an indicator of a particularly strong storm or a possible tornado. Intense wind shear in cumulonimbus clouds that have mammatus make it dangerous for aircraft to enter these clouds.