Mammatus Clouds in East Lansing

Twice this week, East Lansing has been visited by mammatus clouds and hail. Mammatus clouds and hail are not always seen together but they form in the same type of weather systems.

Mammatus clouds are puffy cloud structures that form under large storm clouds like the cumulonimbus clouds that dumped hail on East Lansing twice this week. The pictures above and below show examples of mammatus clouds in East Lansing following the hailstorm yesterday, October 6. These clouds share the same Latin root as “mammal” and “mama.” (Look at the pictures if the reason isn’t clear.)

Although the specific mechanisms behind the formation of mammatus are not a settled matter of science, they are known to only occur in conjunction with big storms with significant wind shear, updrafts, and down drafts. Theories of how these smooth, round, bulbus mammatus form include: areas of cloud cooling and dropping into the air below the cloud; or warm air below the cloud rising up and disrupting the cloud base.

Regardless of the cause, mammatus are evidence of air movement in the cloud similar to air movement required for hail formation. The last photo below shows hail from yesterday’s storm in East Lansing. (ELi previously reported on how hail forms.)

Mammatus are not required for the formation of hail nor are they always present with hailstorms. Likewise, they are not tornadoes and do not form tornadoes although they can be seen in the same kinds of storms that form tornadoes. While mammatus are seen only in large storm clouds, they are not themselves dangerous.

Mammatus cloud images courtesy of Greg Powell.

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