Mamma clouds: What causes these hanging pouches?

Breakdown

• Mamma clouds are pouch-like formations hanging from cloud bases.
• They are often seen beneath cumulonimbus clouds with anvils. 22s
• Formation may involve cold air descending through the cloud base. 28s
• Mamma clouds can also appear on other cloud types and volcanic ash clouds. 35s
• Usually observed at the end of storms, not during them. 43s