Strange and Spectacular Mammatus Clouds
Mammatus Clouds - What Are They?
Mammatus clouds are without doubt one of the weirdest types of cloud you will ever see! They look both simultaneously beautiful (like cotton wool balls) and ominous like the sky is falling!
If you see these surreal Mammatus clouds in the sky and think the end of the world is upon you, don't worry! Mammatus clouds do not signify anything terrible!
This is a guide to how these strange clouds form and where and when you are most likely to see them. Mammatus clouds are a rare occurrence, so you are lucky if you spot them!
A Myth about Mammatus Clouds....
It used to be thought that Mammatus Clouds would descend down and turn into a tornado. This is not true! They disperse after 10-15 minutes.
Facts About Mammatus Clouds - How these weird clouds form
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The Mammatus cloud is an supplementary cloud, which means it is a feature and part of another cloud formation. You may see Mammatus Clouds as a supplementary feature on any of these clouds: Cumulonimbus, Stratocumulus, Altocumulus, Cirrocumulus, Altostratus, Cirrus, and Pycrocumulus.
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The most dramatic formation of Mammatus Clouds can be found on the underside of anvil shaped Cumulonimbus Incus storm clouds. So if you see a Mammatus, does it mean a storm is coming? Meteorologists think not, because Mammatus develop on the rear of the Cumulonimbus after the storm has passed, rather than as the storm is approaching.
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Where do Mammatus clouds get their name? Mammatus means "mammary" in Latin, because these cloud pouches look like udders or breasts!
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The size of each pouch can measure up to two miles across. They are transparent or opaque, so if the sun shines through them they look particularly spectacular! You may see just a cluster of Mammatus, or if you are lucky a "field" of mammatus clouds stretching along for miles. Depending on how intense the wind shear is, the Mammatus clouds can either be organized in neat rows or haphazard groups.
How Do Mammatus Clouds Form?
Reverse direction convection
To understand how the Mammatus cloud forms, you need to understand how a Cumulonimbus Incus cloud develops. Strong updrafts in this anvil shaped cloud cause water particles to be thrust upwards towards the troposphere, up here the cloud cannot grow any higher at this level of our atmosphere so it spreads out - like the picture on the right.
At the very top of the anvil, the water particles have turned into ice. They are denser than the air around them, so start to sink. This is called reverse direction convection. When the ice particles descend, they start to melt slowly but when they reach the base of the Incus, they are still too heavy to evaporate, so they carry on descending through the base of the cloud. This is what creates Mammatus clouds!
Mammatus Clouds on the Base of a Thunderhead - Illustrating the formation of Mammatus
Mammatus Timelapse Video - With amazing lightening!
An In-Depth Study to Mammatus Clouds
My article is a very basic introduction into these amazing clouds. If you want a more in-depth study with a ton of useful info, I recommend:
The Mysteries of Mammatus Clouds: Observations and Formation Mechanisms
