25 Unbelievable Cloud Formations

Posted by on August 9, 2012

Unless you are an avid cloud watcher you may have never even give a second thought to the various shapes and patterns clouds are forming high above your head. While you’ve no doubt seen some of these before there is a good chance others will be completely new. In fact, some are so rare that you will probably never see them apart from lists such as this one. These are 25 unbelievable cloud formations.


Roll Cloud

Often associated with thunderstorms or cold fronts, these clouds are usually low and tube shaped.


Shelf Clouds

Also associated with cold fronts and thunderstorms, shelf clouds differ from roll clouds in that they are usually attached to the parent cloud directly above.


Cirrus Kelvin-Helmholtz

These slim, horizontal spirals tend to dissipate quickly after their initial formation making observation difficult.


Mammatus Clouds

These rare pouch-like clouds usually form after the thunderstorm has passed. Contrary to common knowledge they do not indicate an imminent tornado (although they do look ominous).


Nacreous Clouds

Sometimes referred to as “mother of pearl” clouds, these can be found at altitudes of up to 20 miles. Usually seen in polar regions near the poles they are known for their iridescent colors.


Pileus Clouds

Also known as scarf or cap clouds, these high flying clouds generally hover over the top of larger cumulonimbus clouds.


Actinoform Clouds

Hard to see with the naked eye, this formation is best observed from space. In satellite images they have a distinct leaf or wheel like pattern that sets them apart from the background.


Wave Clouds

These clouds are usually formed by waves of air that flow over a raised land feature such as a mountain range.


Pyrocumulus Cloud

Sometimes called fire clouds these dense cumuliform clouds are associated with fires or volcanic activity.


Undulatus Asperatus

Proposed to be a separate cloud formation in 2009, if it is accepted International Cloud Atlas of the World Meteorological Organization then it will be the first addition since 1951.


Cumulus Arcus

Although both rolling and shelf clouds fall into this category, there are several others less famous types as well.


Cumulonimbus Capillatus

This umbrellas category includes any towering vertical cloud with a high cirriform top


Cirrus spissatus

The highest of the primary cloud genera, this cirrus variety is formed out of fine wisps of ice crystals.



Although they are not naturally occurring cloud formations, these vapor trails are technically a type of cirrus cloud known as cirrus aviaticus


Morning Glory Clouds

This rare phenomenon is hard to observe due to its unpredictable nature. In fact, the only place where it occurs consistently is northern Australia.