ICA Vol II

[Howard Brown]

Well, this was a big surprise for me – I have the book and often delve into it, the pictorial part of the International Cloud Atlas (ICA). I was actually looking up nacreous pp 163/164:

https://www.metabunk.org/attachments/wmo_407_en-v2-pdf.4000/

Colin, thank you for your mammatus news extra, I have yet to check it out.

Nacreous is in the Vol II index as Special Cloud. Mammatus I could not see – the index is of the cloud types in the photo, so genus and species stands out, the occasional Accessory Cloud/Supplementary Feature not so much.

[Dillon Browne]

Hygge, thanks for posting that link to the ICA Vol II. I’ve not seen the ICA before and appreciate being able to check out the photos with detailed explanations.

With reference to the mammatus, you may have already seen that they appear as an ‘extra’ feature of other cloud types. Going through the book they appear on pages 27 (Stratocumulus stratiformis) and pages 47 & 48 under Cumulonimbus. I also note that in The Cloudspotter’s Guide they appear as ‘Supplementary Features’. So not actually a species in their own right. I saw my first example only last year right over our house at the tail-end of a thunderstorm. Very impressive.

[Howard Brown]

Oh, well read, Airhead. That’s impressive. I still have to read Colin’s news extra.

For AK: as I must have mentioned in the distant past, page 126 is at Bishop, Ca, ‘Fohn wall, rotor clouds and orographic Altocumulus lenticularis’. We are lucky AK so often records such phenomena in the Owens Valley for CAS.

[Graham Davis]

When I first joined the Met Office (July 1962), the station where I was working had a copy of the ICA that dated from the 1950s. In this, there was a photograph of Stratocumulus castellanus. Later versions of the Atlas have airbrushed that cloud out of existence. I’ve always wondered why this happened as I’ve seen almost as many examples of the cloud as I have of the higher variety.

[Howard Brown]

Graham, I can confirm that the ICA Vol I revised edition 1975 has Sc cas (but floccus was not introduced); possibly not the Vol II 1987, unless Airhead knows better.

All the books I have checked have Sc cas.

The (probably 1982) PDF should have Sc cas in CL 5 around p8 (different on-line)
http://www.metoffice.gov.uk/media/pdf/r/i/Cloud_types_for_observers.pdf

That leaves later on-line Met Office docs meant for the more casual observer – perhaps they are your problem, Graham? I have not checked them.

I only wish I could add my own observations, but I seem to be blind to cas.

‘H’

[Graham Davis]

‘H’, thanks for that link. I hadn’t checked ICA Vol 1 so hadn’t spotted that still had Sc cas, shame that Vol 2 doesn’t seem to have a photo.

Not too sure about that photo in the Met Office publication as it could be Ac cas. Ac cas can look a lot lower than it really is because of the larger size of the elements.

I’ve found that Sc cas often makes its appearances in the early morning, shortly after dawn, when I think it may be the remains of cumulus that has formed over the sea but has spread out into Sc when it has moved over the land. In this case, although there is no heat from the surface to maintain convection, there may be processes going on at the cloud level, such as convergence or orograhic lifting, that could kick it off again so that fresh turrets form from the Sc.

[Dillon Browne]

Well, ‘H’, you set me a challenge a few days ago and I think I have to agree with Graham’s suspicion that Sc cas had been airbrushed out. Loads of Ac cas – more than you can throw a stick at. But no Sc cas.

Having spent more than a few minutes scanning the ICA Vol II I am struck by the beauty of some of the pictures. Many worthy of the CAS Gallery. In particular the Cirrocumulus stratiformis undulatus on P.117. The photo of Ground Fog on P.176 by R.K.Pilsbury is I think a work of art.

R.K.Pilsbury – I couldn’t help but notice that R.K.Pilsbury took plenty of photos for the volume, over 20. It looks from the locations that he worked for the Met Office at least from 1972-82. I note as well from Amazon that he wrote Clouds and Weather (1970). I wondered if you know of him Graham?

[Howard Brown]

Thanks for that, Airhead (my apologies for my habit of setting challenges for others). It is interesting that you lighted upon RK Pilsbury – I did too, and I have that book but dated 1969 (acquired on the second-hand market). Also, several of those ICA II pictures by RKP were taken on the Isle of Wight within my local region – so I figured there must be something interesting around and joined CAS in 1/07 to find out more.

In the book he mentions two pictures of noctilucent cloud taken by himself at Swansea and his daughter at Bracknell on the night of 27/28 June 1966 which enabled him to calculate that the cloud was 84 km high roughly over Dublin. GP-P checked CAS membership records (after 1/07) and there was no Pilsbury.

‘H’

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