What are Mammatus clouds?

About Mammatus clouds:

• Mammatus clouds refer to distinctive cloud formations that are separated by a bulge or protrusion emerging from the base of another cloud.
• They are usually formed in association with large cumulonimbus clouds.
• Typically, turbulence within the cumulonimbus cloud will cause Mammatus to form, especially on the underside of the projecting anvil as it rapidly descends to lower levels.
• Mammatus clouds generally form in the most unstable cumulonimbus, meaning that there is also a chance of hail, heavy rain and lightning in the vicinity, and if the air is cold enough during winter they can produce snow.