Mammatus cloud

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Mammatus cloud
Mammatus clouds in Regina, Saskatchewan
Mammatus clouds in Regina, Saskatchewan
AppearanceThe cloud appears to have smooth, round puffs hanging from its underside.
Precipitation cloud?No
 
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Mammatus cloud
Mammatus clouds in Regina, Saskatchewan
Mammatus clouds in Regina, Saskatchewan
AppearanceThe cloud appears to have smooth, round puffs hanging from its underside.
Precipitation cloud?No

Mammatus, also known as mammatocumulus (meaning "mammary cloud" or "breast cloud"),[1][2] 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 (meaning "udder" or "breast").

Characteristics[edit]

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.[citation needed] 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 translucent. Because mammatus occur as a grouping of lobes, the way they clump together can vary from an isolated cluster to a field of mammae 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.

True to their ominous appearance, mammatus clouds are often harbingers of a coming storm or other extreme weather system. Typically composed primarily of ice, they can extend for hundreds of miles in each direction and individual formations can remain visibly static for ten to fifteen minutes at a time. While they may appear foreboding they are merely the messengers - appearing around, before or even after severe weather.

Hypothesized formation mechanisms[edit]

The existence of many different types of mammatus clouds, each with distinct properties and occurring in distinct environments, has given rise to multiple hypothesized formation mechanisms, which are also relevant to other cloud forms.

One environmental trend is shared by all of the formation mechanisms hypothesized for mammatus clouds: sharp gradients in temperature, moisture and momentum (wind shear) across the anvil cloud/sub-cloud air boundary, which strongly influence interactions therein. The following are the proposed mechanisms, each described with its shortcomings:

This plenitude of proposed formation mechanisms shows, if nothing else, that the mammatus cloud is generally poorly understood. Detailed observations of the cloud have been meager and usually occur only by chance, since mammatus do not pose a meteorological threat to society.[citation needed]

Gallery[edit]

References[edit]

  1. ^ http://weatherwing.com/Cumulonimbus-Mammatus.html
  2. ^ http://www.erh.noaa.gov/er/pit/mam98.htm

External links[edit]