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A look at mammatus clouds

Updated: May 22, 2022

Mammatus are likely one of the more majestic and distinctive clouds you will ever witness. They are actually not all that rare. When they occur near sunrise or sunset, they can almost look unreal. So it's not surprising that they have appeared in many paintings over the last few centuries and are common to see plastered all over social media. Just go to #mammatus on Twitter and you'll certainly get your fill of amateur photographers that have captured these clouds. But what causes the distinctive shape to these clouds and what do they mean to you as a pilot?

Photo courtesy of Roger Roberts

Mammatus get their name from the Latin for mamma (meaning "udder" or "breast"). They are most commonly observed on the underside of cumulonimbus anvils so pilots tend to see these as a warning for severe or extreme convective turbulence. But, but they have also been observed under cirrus, cirrocumulus, altocumulus, altostratus, and stratocumulus, as well as in contrails. Perhaps the most awe-inspiring mammatus are those associated with pyrocumulus ash clouds from volcanic eruptions as was seen below after the eruption of Mount St. Helens in 1980.

Surprisingly, we still have a long way to go before we can understand the underlying properties of these clouds. There have been very few studies done with regard to these clouds with hanging protuberances, however, there are many untested theories. In the end, published research is very limited a