Andy Perrin Posted June 9, 2020 Share Posted June 9, 2020 R72 filter on EL-Nikkor 80mm/5.6. But this is a pano. Likely a Kelvin-Helmholtz cloud. Link to comment
dabateman Posted June 9, 2020 Share Posted June 9, 2020 Great image.I used to know the different cloud types. But I have some how knocked that information from my head. You maybe seeing Altocumulus clouds there. Before or after a thunderstorm somewhere near by. I tried to learn the cloud types when I first got into IR. As to predict the best background on a day I might head out. Now you can just add anything in software. Link to comment
Bill De Jager Posted June 9, 2020 Share Posted June 9, 2020 Great image.I used to know the different cloud types. But I have some how knocked that information from my head. You maybe seeing Altocumulus clouds there. Before or after a thunderstorm somewhere near by. I think Andy is talking about this https://en.wikipedia.org/wiki/Kelvin%E2%80%93Helmholtz_instability which can involve various types of clouds. Link to comment
Andy Perrin Posted June 9, 2020 Author Share Posted June 9, 2020 Bill is correct. It's not a specific cloud type, in fact the instability is in the *air*, and the cloud just provides a visualization. Thanks everyone! Link to comment
Andrea B. Posted June 10, 2020 Share Posted June 10, 2020 Clouds are so cool in IR. Has anyone ever visited the Cloud Appreciation Society's gallery? Linkie: https://cloudappreciationsociety.org/gallery/Beautiful photographs there. At the upper right there is a photo icon which provides a menu of cloud types. There were more examples of the Kelvin-Helmholtz effect which Andy shows.I particularly love lenticular formations, "flying saucer" clouds. Link to comment
dabateman Posted June 11, 2020 Share Posted June 11, 2020 No I hadn't seen that before.Circumhorizon Arc, is what I was seeing a couple of months ago. But only with polarizers on. I tried to catch a UV image but lost it in the camera setup time. Link to comment
JMC Posted June 11, 2020 Share Posted June 11, 2020 Funky clouds. The linear pattern reminds me a bit of some I saw at Saqqara in Egypt in 2000. Ah fun times - that was the trip I bought my first SLR camera for....... Link to comment
OlDoinyo Posted June 13, 2020 Share Posted June 13, 2020 There are certainly multiple K-H features visible in the first photo, but I have not heard it as a standalone term for a cloud type. I don't know if the formation might be a form of asperitas. The second photo looks like a train of rotor clouds in the lee of a mountain wave. Link to comment
Andy Perrin Posted June 13, 2020 Author Share Posted June 13, 2020 K-H is a type of instability. My use of the term “K-H cloud” was purely colloquial. I have seen them called that by others in the past but I don’t think it’s a recognized cloud type. K-H instability happens any time you have a rapid change in velocity between two layers of air, regardless of whether a cloud is present to SEE it or not. Please enjoy my computer simulation of a K-H instability here: https://youtu.be/SAAuE_LN6jo Link to comment
Andrea B. Posted June 18, 2020 Share Posted June 18, 2020 Love that, Andy. Thanks for the link. The K-H effect reminds me of that old Greek pattern: meander.(I had to blunder around to find that because I never knew it had a name until now.) And this: https://buffaloah.com/a/DCTNRY/v/vitwave.html Link to comment
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