Difference between Calvus and Congestus ?

[Moser]

Hi, I have difficulties spotting any difference between cumulus congestus and cumulonimbus calvus. What are they ? I know that calvus is supposed to have a smoother "head" but it does not help me. Can someone show me two pictures showing clear differences ? Maybe that the difference between calvus and congestus are only semantic and that both clouds are almost indiscernible. Thanx !

[Lettucing Gutted]

Cumulonimbus Calvus indeed have smoother heads than Cumulus Congestus as well as softer heads.  This is because at least the upper part of Cumulonimbus Calvus contains individual ice crystals and even full snowflakes.  In fact in classic unstable Arctic outbreaks with little modification that occur in winter and even spring and autumn, Cumulonimbus Calvus are very common and consists almost entirely of snowflakes and ice crystals.  Cumulus Congestus on the other hand consist almost entirely of rain and supercooled water droplets which gives these clouds hard and rough tops.  In the tropics due to the very high freezing levels and muggy and thick troposphere, Cumulus Congestus clouds grow to altitudes many times greater than the small Cumulonimbus Incus clouds which build in the unstable and icy and thin troposphere over seas near the poles as well as in winter over mid latitudes in unstable arctic air.

[Terminal Moraine]

On 20/07/2017 at 08:50, Moser said:

Hi, I have difficulties spotting any difference between cumulus congestus and cumulonimbus calvus. What are they ? I know that calvus is supposed to have a smoother "head" but it does not help me. Can someone show me two pictures showing clear differences ? Maybe that the difference between calvus and congestus are only semantic and that both clouds are almost indiscernible. Thanx !

Here are a couple of links to photo's which may help.

https://en.wikipedia.org/wiki/Cumulonimbus_calvus

https://en.wikipedia.org/wiki/Cumulus_congestus_cloud

[Moser]

On 22/7/2017 at 18:31, Terminal Moraine said:

Here are a couple of links to photo's which may help.

https://en.wikipedia.org/wiki/Cumulonimbus_calvus

https://en.wikipedia.org/wiki/Cumulus_congestus_cloud

Thanx for your messages but this kind of article does not help me. I still cannot distinguish the difference between theses 2 kinds of clouds...

[Terminal Moraine]

It's not the easiest distinction to make as there comes a point when Cumulus congestus, if it continues to build, becomes Cumulonimbus calvus. Generally speaking Cumulus congestus are smaller and less 'beefy' looking than Cumulonimbus calvus and have very sharply defined tops. In Cumulonimbus calvus, as has been mentioned above, the sharply defined tops are starting to become smoothed out. Ultimately there is a certain amount of subjectivity involved as to whether the cloud is Cumulus congestus or Cumulonimbus calvus when the point of transition between the two is near. 

[Lettucing Gutted]

As well as the ability to produce snow showers, there are other phenomena that differentiate Cumulonimbus Calvus from Cumulus Congestus.  Cumulonimbus Calvus can produce hail and/thunderstorms however Cumulus Congestus doesn't have enough ice crystals, graupel or ice pellets for another of these to occur.  Strong tornadoes are reserved exclusively for Cumulonimbus clouds whilst Cumulus Congestus can only rarely even produce weak tornadoes or waterspouts.