Quite common above mountainous terrain, I saw one that had 9 layers near the eastern pyrenees a couple of years ago. They give some insight into how the atmosphere is not just an amorphous mass of air but is made up of layers of different humidity.
Being a tad quirky I belong to The Cloud Appreciation Society.....which means as well as spending lots of time lying on my back in the garden looking at the sky I get newsletters with pictures of fascinating clouds......☺
Gness, a very large fallstreak occurred over our village a few days ago, I posted a photo of it up on my facebook page...people were amazed but so far I appear to be the only person in the village that saw it. It only covered about half of the sky and laste half an hour!
@jomifl I had never heard of fall-streak holes until a couple of years ago. I now see them about twice a year so I must have seen them before without realising what they were. I posted the first one on Blipfoto:
https://www.polaroidblipfoto.com/entry/2543802
@gen2, I only came across them when I bought the cloud appreciation society's handbook. I've seen little ones a long way off but this was almost overhead. Similar to yours but a bit younger perhaps?