The clouds above – Part Six

Everything you need to know about clouds – the end of the story!

Everything you need to know about clouds

August 13, 2018.

Special clouds

Some clouds only form as a result of localized conditions or due to human activity.

The 2013 Powerhouse Fire in California produced flammagenitus clouds. (Photo: Chevy111/Wikimedia Commons)

1. Flammagenitus. These clouds develop as a result of forest fires, wildfires and volcanic eruptions.

Homogenitus clouds, like the ones emitted from this coal-fired power plant, are created by human activity. (Photo: thelefty/Shutterstock)

2. Homogenitus. If you’ve ever driven by a factory with a kid and they’ve shouted “Cloud factory!”, they have identified homogenitus clouds. This type of special cloud covers a range of man-made clouds, including rising thermals from power plants.

A contrail streaks out of some clouds. (Photo: G. Larson/Wikimedia Commons)

3. Aircraft condensation trails. Contrails are a special type of the homogenitus special cloud. They must have persisted for 10 minutes to be dubbed cirrus homogenitus.

A cirrus homomutatus, or a persistent contrail cloud, over Lille, France. (Photo: Lamiot/Wikimedia Commons)

4. Homomutatus. If contrails persist and begin to grow and spread over a period of time thanks to strong winds, they become homomutatus clouds.

Clouds form near a waterfall in Iceland. (Photo: Francesco Carucci/Shutterstock)

5. Cataractagenitus. These clouds form near waterfalls, the result of water broken up into a spray by the falls.

Silvagenitus clouds form over forests. (Photo: Glenn R. Specht-grs photo/Shutterstock)

6. Silvagenitus. Clouds may form over a forest as the result of increased humidity and evaporation.

Supplementary features

The final bit of cloud identification involves supplementary features that are attached to or merged with the cloud.

You could forge a horseshoe cloud on that thing. (Photo: Simon Eugster/Wikimedia Commons)

1. Incus. The spread-out, anvil-like portion at the top of a cumulonimbus cloud.

Mamma clouds appear over Leuven, Belgium. (Photo: Bart De Bruyn/Wikimedia Commons)

2. Mamma. Those hanging protuberances are called mamma, and they appear along the bottom of cirrus, cirrocumulus, altocumulus, altostratus, stratocumulus and cumulonimbus clouds.

These altocumulus clouds have virga trails along their bottoms. (Photo: Kr-val/Wikimedia Commons)

3. Virga. If a cirrocumulus, altocumulus, altostratus, nimbostratus, stratocumulus, cumulus or cumulonimbus cloud looks a bit like a jellyfish, chances are they have a virga feature. These are precipitation trails, or fallstreaks, and the precipitation never reaches the Earth’s surface.

Grab an umbrella, a cloud has a praecipitatio feature. (Photo: Silar/Wikimedia Commons)

4. Praecipitatio. If that precipitation makes it to Earth, however, then you have a praecipitatio feature on an altostratus, nimbostratus, stratocumulus, stratus, cumulus and cumulonimbus cloud.

Clouds with arcus features are pretty scary. (Photo: Sensenmann/Wikimedia Commons)

5. Arcus. These cumulonimbus clouds (and sometimes cumulus) feature dense horizontal rolls with tattered edges along the front. When the arcus feature is extensive, the roll can have a “dark, menacing arch.”

Tuba accessory clouds look like funnels reaching out from the clouds. (Photo: 7alaskan/Wikimedia Commons)

6. Tuba. This cone protrudes from the cloud base and is the marker of a intense vortex. Like arcus clouds, tubas appear most often with cumulonimbus and sometimes with cumulus.

Varying levels of illumination and thickness of asperitas clouds can lead to dramatic visual effects. (Photo: WikiRigaou/Wikimedia Commons)

7. Asperitas. While they look like undulatus clouds, asperitas supplementary clouds are more chaotic and less horizontal. Still, these supplementary clouds for stratocumulus and altocumulus clouds make it look like the sky has become a rough and choppy sea.

Fluctus clouds appear along the top of certain clouds. (Photo: Grahamuk/Wikimedia Commons)

8. Fluctus. These are short-lived, wave-looking supplementary clouds that appear with cirrus, altocumulus, stratocumulus, stratus and sometimes cumulus clouds.

Vigra or wispy cirrus clouds often fall from the central hole. (Photo: H. Raab/Wikimedia Commons)

9. Cavum. Also known as a fallstreak hole, cavum are supplementary clouds for altocumulus and cirrocumulus clouds. They’re formed when the water temperature in the cloud is below freezing but the water itself has not frozen yet. When the ice does eventually form, water droplets around the crystals evaporate, leaving the large ring. Interaction with aircraft can result in a straight line cavum instead of a circular one.

Tuba clouds will sometimes spout from murus clouds. (Photo: Giorgio Galeotti/Wikimedia Commons)

10. Murus. Typically associated with supercell storms, murus (or wall clouds) develop in the rain-free portions of cumulonimbus clouds. They mark a place of strong updraft from which tornadoes can sometimes form.

A wall cloud with a tail cloud. (Photo: NOAA/OAR/ERL/National Severe Storms Laboratory/Wikimedia Commons)

11. Cauda. Cauda are an accessory cloud to an accessory cloud, appearing alongside murus clouds. These horizontal, tail-like clouds are attached to the murus, and they are roughly the same height. They should not be confused with a funnel.


And that, dear friends, is it!

Truly, how many of you stayed with all the episodes?

I must close by thanking both Mother Nature Network and Noel Kirkpatrick for putting together such a brilliant reference article.

Now watch out! You are just about to walk into that lamp-post!!

4 thoughts on “The clouds above – Part Six

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