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Clouds and intermediate forms

Rich West

EF0
Joined
Feb 9, 2012
Messages
27
When I got my first cloud book I thought that the classification system would be really easy and so went out and looked up....in the 9 months since I often see varied sky's that look like intermediates between forms. For example, the boundary between stratus and stratocumulus seems to have thousands of intermediate variations..the cumulus /Sc boundary is also hard to judge..I have seen tw o met websites with the same picture- one labelled as c and the other as sc.

What do folks think?

Cheers

Rich
 
That picture I saw was just an example of the whole issue...I didnt save the pic nor the website details. I was hoping that, either, others had looked up and drawn the same conclusions or would be able to point out my mistakes via their own sky watching. Cheers.
Rich
 
Stupid natural phenomena. If clouds are allowed to vary from the established norms, what'll be next? Mass chaos!

Headline: "County Officials Critical of Indecisive Clouds". I'm thinking some sort of cumulus certification program may be in order.
 
Well that is really my point! Some of the meteorologists I have spoken to dont seem to agree and want to classify all clouds in the basic forms, which for scientific communication is quite natural and normal- as long as it doesnt miss anything useful out.

So for anyone that wishes to engage I would ask "where amongst these myriad of transitional forms do we find the classification change? Are there pictures anywhere of these forms and guidelines for these change points?"

All the best

Rich
 
Cloud identification and classification is one of the things that has become a lost art since the automation of the observational side of meteorology. We spent a lot of time on this during block one instruction at Chanute, back in the day. And it was also a big part of the certification process when you were assigned to your first duty station. Over time, you began to realize that not every sky con for every ob you took was going to fit neatly into one of the 27 states of the sky. The idea was to find the predominate cloud cloud and encode it according to the priority set forth by international standards and in accordance with the level (low, mid or high) the cloud was classified in. For instance, you could have a low cloud 7 (stratus/stratus fractus of bad weather) and a low cloud 9 (cumulonimbus with anvil present.) In that case, the low 9 would be the priority which you would encode for the 1ClCmCh group.

Here's a link to a version of an excellent manual we use to have in every office call "Cloud Types for Observers." It should give you a good idea of the classification scheme as it relates to surface weather observations:

http://www.metoffice.gov.uk/media/pdf/r/i/Cloud_types_for_observers.pdf
 
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Clouds are constantly changing which can make identification tricky at times, especially if you have not been watching that particular cloud for awhile. I find that determining whether it is building or disipating can help to sometimes ID a tricky one, but as with many other natural phenomeon, there will always be some that do not appear to fit into our classifications.
 
As a TV met, I don't usually get all caught up in defining cloud terms to the audience, though do try to point out ACCAS and such cloud types that can be a harbinger of things to come.

At the same time, I AM Mr. No Depth Perception and often am not quite sure of altitude. I simply go looks up METARs from a few of the local manned airports to see what the ASOS or observer is reporting.

That can help in determining cloud type, though there are no hard-and-fast altitudes at which cumulus becomes alto-cu, etc. etc. Sometimes cloud type is really in the eye of the beholder! (and that Met office manual is oustanding Mike, thanks for sharing!)
 
Rich West said:
the boundary between stratus and stratocumulus seems to have thousands of intermediate variations..the cumulus /Sc boundary is also hard to judge..I have seen tw o met websites with the same picture- one labelled as c and the other as sc.

What do folks think?

Cheers

Rich
Click to expand...

Cloud height is a big determining factor. Layered clouds under 1500feet are stratus. For the inexperienced eye it can be difficult to judge clouds heights though. Stratocumulus forms under an inversion between 1500 and 6000feet. You can look at a sounding to check for the inversion.
 
Thank you very much, chaps, partic Mike for the excellent pdf link.

My ability to judge height is pretty poor, and here I have also noticed supposedly rare forms making things more difficult, so I shall print off the acrobat file and keep practicing. Cheers again all.

Rich
 
Hey Mike, I remember going through the same type of instruction down in Keesler AFB, when i was in Observing school. It took me 3 to 4 weeks to get the cloud types down pat, trying to judge the heights and determining what type of cloud it was. I think it was fairly simple to distinguish between high and mid clouds because of texture and movement. But making the distinction between low and mid decks was a bit harder. For us making the distinction of Low Cloud 3 or Low Cloud 9 was the tough part. Oh yeah, we always went with the standard 8/963 for thunderstorms....
 
Yea, a low 3 was hard to determine unless it was close enough to station to determine if it was producing precipitation/lightening and thunder or not as well as it's nature being transitory from a low 2 to a low 9. Coding altocu was also troublesome at times so it was always good to have the mid 7 as a catch-all. :-)
 
Cheers Steven. That's an interesting fact.

Is there a way to post pics on these threads anyone for comment?

Thanks to all the people who have chipped in so far :)

All the best

Rich
 
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